Health regen script wont work properly

    var gotHitTimer=0;
var regentimer=0;
var hurtsound : AudioClip;
var waittime=5;
var healthlastframe :float = 100;
var walkSpeed = 6.0;
var respawnpoint : GameObject;
var runSpeed = 11.0;
var dietimes = 0;
// If true, diagonal speed (when strafing + moving forward or back) can't exceed normal move speed; otherwise it's about 1.4 times faster
var limitDiagonalSpeed = true;
var shadap : AudioClip;
// If checked, the run key toggles between running and walking. Otherwise player runs if the key is held down and walks otherwise
// There must be a button set up in the Input Manager called "Run"
var toggleRun = false;
var health :float =100;
var jumpSpeed = 8.0;
var gravity = 20.0;

// Units that player can fall before a falling damage function is run. To disable, type "infinity" in the inspector
var fallingDamageThreshold = 10.0;

// If the player ends up on a slope which is at least the Slope Limit as set on the character controller, then he will slide down
var slideWhenOverSlopeLimit = false;

// If checked and the player is on an object tagged "Slide", he will slide down it regardless of the slope limit
var slideOnTaggedObjects = false;

var slideSpeed = 12.0;

// If checked, then the player can change direction while in the air
var airControl = false;

// Small amounts of this results in bumping when walking down slopes, but large amounts results in falling too fast
var antiBumpFactor = .75;

// Player must be grounded for at least this many physics frames before being able to jump again; set to 0 to allow bunny hopping
var antiBunnyHopFactor = 1;

private var moveDirection = Vector3.zero;
private var grounded = false;
private var controller : CharacterController;
private var myTransform : Transform;
private var speed : float;
private var hit : RaycastHit;
private var fallStartLevel : float;
private var falling = false;
private var slideLimit : float;
private var rayDistance : float;
private var contactPoint : Vector3;
private var playerControl = false;
private var jumpTimer : int;

function Start () {
    controller = GetComponent(CharacterController);
    myTransform = transform;
    speed = walkSpeed;
    rayDistance = controller.height * .5 + controller.radius;
    slideLimit = controller.slopeLimit - .1;
    jumpTimer = antiBunnyHopFactor;
    oldPos = transform.position;
}

function FixedUpdate() {
    var inputX = Input.GetAxis("Horizontal");
    var inputY = Input.GetAxis("Vertical");
    // If both horizontal and vertical are used simultaneously, limit speed (if allowed), so the total doesn't exceed normal move speed
    var inputModifyFactor = (inputX != 0.0 && inputY != 0.0 && limitDiagonalSpeed)? .7071 : 1.0;

    if (grounded) {
        var sliding = false;
        // See if surface immediately below should be slid down. We use this normally rather than a ControllerColliderHit point,
        // because that interferes with step climbing amongst other annoyances
        if (Physics.Raycast(myTransform.position, -Vector3.up, hit, rayDistance)) {
            if (Vector3.Angle(hit.normal, Vector3.up) > slideLimit)
                sliding = true;
        }
        // However, just raycasting straight down from the center can fail when on steep slopes
        // So if the above raycast didn't catch anything, raycast down from the stored ControllerColliderHit point instead
        else {
            Physics.Raycast(contactPoint + Vector3.up, -Vector3.up, hit);
            if (Vector3.Angle(hit.normal, Vector3.up) > slideLimit)
                sliding = true;
        }

        // If we were falling, and we fell a vertical distance greater than the threshold, run a falling damage routine
        if (falling) {
            falling = false;
            if (myTransform.position.y < fallStartLevel - fallingDamageThreshold)
                FallingDamageAlert (fallStartLevel - myTransform.position.y);
        }

        // If running isn't on a toggle, then use the appropriate speed depending on whether the run button is down
        if (!toggleRun)
            speed = Input.GetButton("Run")? runSpeed : walkSpeed;

        // If sliding (and it's allowed), or if we're on an object tagged "Slide", get a vector pointing down the slope we're on
        if ( (sliding && slideWhenOverSlopeLimit) || (slideOnTaggedObjects && hit.collider.tag == "Slide") ) {
            var hitNormal = hit.normal;
            moveDirection = Vector3(hitNormal.x, -hitNormal.y, hitNormal.z);
            Vector3.OrthoNormalize (hitNormal, moveDirection);
            moveDirection *= slideSpeed;
            playerControl = false;
        }
        // Otherwise recalculate moveDirection directly from axes, adding a bit of -y to avoid bumping down inclines
        else {
            moveDirection = Vector3(inputX * inputModifyFactor, -antiBumpFactor, inputY * inputModifyFactor);
            moveDirection = myTransform.TransformDirection(moveDirection) * speed;
            playerControl = true;
        }

        // Jump! But only if the jump button has been released and player has been grounded for a given number of frames
        if (!Input.GetButton("Jump"))
            jumpTimer++;
        else if (jumpTimer >= antiBunnyHopFactor) {
            moveDirection.y = jumpSpeed;
            jumpTimer = 0;
        }
    }
    else {
        // If we stepped over a cliff or something, set the height at which we started falling
        if (!falling) {
            falling = true;
            fallStartLevel = myTransform.position.y;
        }

        // If air control is allowed, check movement but don't touch the y component
        if (airControl && playerControl) {
            moveDirection.x = inputX * speed * inputModifyFactor;
            moveDirection.z = inputY * speed * inputModifyFactor;
            moveDirection = myTransform.TransformDirection(moveDirection);
        }
    }

    // Apply gravity
    moveDirection.y -= gravity * Time.deltaTime;

    // Move the controller, and set grounded true or false depending on whether we're standing on something
    grounded = (controller.Move(moveDirection * Time.deltaTime) & CollisionFlags.Below) != 0;
}

function Update () {
    // If the run button is set to toggle, then switch between walk/run speed. (We use Update for this...
    // FixedUpdate is a poor place to use GetButtonDown, since it doesn't necessarily run every frame and can miss the event)
    if (toggleRun && grounded && Input.GetButtonDown("Run")){
        speed = (speed == walkSpeed? runSpeed : walkSpeed);
     }
     if (health<1){
     audio.PlayOneShot(shadap);
      transform.position = respawnpoint.transform.position;
      health=100;
      }
      if(health<100){
         regen();   

     }
  if(health>100){
  health=100;
  }

   Camera.main.GetComponent("ColorCorrectionEffect").rampOffsetR = (100-health)/150;

   if(health!=healthlastframe){
regenwait();
}
}
// Store point that we're in contact with for use in FixedUpdate if needed
function OnControllerColliderHit (hit : ControllerColliderHit) {
    contactPoint = hit.point;
}

// If falling damage occured, this is the place to do something about it. You can make the player
// have hitpoints and remove some of them based on the distance fallen, add sound effects, etc.
function FallingDamageAlert (fallDistance : float) {
    Debug.Log ("Ouch! Fell " + fallDistance + " units!");   
if(fallDistance>20)
   health=health-fallDistance/1.5;

}
function OnGUI () {
    GUI.Label (Rect (30, 80, 100, 30), health.ToString());

}
function Awake(){
 transform.position = respawnpoint.transform.position;
}
function regen(){

            while(regentimer==1){
              health+=3;
              yield;
             }

            if(health>100){
              health=100;
                 }
    }

function regenwait(){
regentimer=0;
playhurtsound();
addblur();
regentimer=0;
yield WaitForSeconds(10);
regentimer=1;
healthlastframe = health;
}

function addblur(){
camera.main.GetComponent("BlurEffect").enabled=true;
yield WaitForSeconds(1);
camera.main.GetComponent("BlurEffect").enabled=false;
}

function playhurtsound(){
if (Time.time > gotHitTimer) {
audio.PlayOneShot(hurtsound);
}
gotHitTimer = Time.time + hurtsound.length;

}

@script RequireComponent(CharacterController)

Okay , in this script , i wait 10 seconds to start regenerating . I then regenerate but when im at 100 hp i continue regenerating for another 10 seconds. Also when im hit while regenerating i dont stop another 10 seconds but continue to regenerate. What am i doing wrong here?

Basically I'd get rid of all the yields you've got and use time stamps instead. Find the time that you were last hit and then only start regaining health when the game time is 10 seconds higher than the time stamp.

Change your regen script to this:

 function ApplyDamage(points : float){
       AddBlur();
       health-=points;
       lastHit = Time.time;
       health = Mathf.Clamp(health,0,100); // clamp health
       if(health<=0)
          //dead
    }

    function Regen(){
       // start 10 seconds after the last time you were hit
       if(Time.time-lastHit>10){
          // regain 3 hit points every second
          health+=Time.deltaTime*3;
          health = Mathf.Clamp(health,0,100); // clamp health
       }
    }

Health is a float here but you can change my script to work with yours.

EDIT

Included AddBlur

var lastHit;
var gotHitTimer=0;
var regentimer=0;
var hurtsound : AudioClip;
var waittime=5;
var walkSpeed = 6.0;
var respawnpoint : GameObject;
var runSpeed = 11.0;
var dietimes = 0;
// If true, diagonal speed (when strafing + moving forward or back) can't exceed normal move speed; otherwise it's about 1.4 times faster
var limitDiagonalSpeed = true;
var shadap : AudioClip;
// If checked, the run key toggles between running and walking. Otherwise player runs if the key is held down and walks otherwise
// There must be a button set up in the Input Manager called "Run"
var toggleRun = false;
var health :float =100;
var jumpSpeed = 8.0;
var gravity = 20.0;

// Units that player can fall before a falling damage function is run. To disable, type "infinity" in the inspector
var fallingDamageThreshold = 10.0;

// If the player ends up on a slope which is at least the Slope Limit as set on the character controller, then he will slide down
var slideWhenOverSlopeLimit = false;

// If checked and the player is on an object tagged "Slide", he will slide down it regardless of the slope limit
var slideOnTaggedObjects = false;

var slideSpeed = 12.0;

// If checked, then the player can change direction while in the air
var airControl = false;

// Small amounts of this results in bumping when walking down slopes, but large amounts results in falling too fast
var antiBumpFactor = .75;

// Player must be grounded for at least this many physics frames before being able to jump again; set to 0 to allow bunny hopping
var antiBunnyHopFactor = 1;

private var moveDirection = Vector3.zero;
private var grounded = false;
private var controller : CharacterController;
private var myTransform : Transform;
private var speed : float;
private var hit : RaycastHit;
private var fallStartLevel : float;
private var falling = false;
private var slideLimit : float;
private var rayDistance : float;
private var contactPoint : Vector3;
private var playerControl = false;
private var jumpTimer : int;

function Start () {
    controller = GetComponent(CharacterController);
    myTransform = transform;
    speed = walkSpeed;
    rayDistance = controller.height * .5 + controller.radius;
    slideLimit = controller.slopeLimit - .1;
    jumpTimer = antiBunnyHopFactor;
    oldPos = transform.position;
}

function FixedUpdate() {
    var inputX = Input.GetAxis("Horizontal");
    var inputY = Input.GetAxis("Vertical");
    // If both horizontal and vertical are used simultaneously, limit speed (if allowed), so the total doesn't exceed normal move speed
    var inputModifyFactor = (inputX != 0.0 && inputY != 0.0 && limitDiagonalSpeed)? .7071 : 1.0;

    if (grounded) {
        var sliding = false;
        // See if surface immediately below should be slid down. We use this normally rather than a ControllerColliderHit point,
        // because that interferes with step climbing amongst other annoyances
        if (Physics.Raycast(myTransform.position, -Vector3.up, hit, rayDistance)) {
            if (Vector3.Angle(hit.normal, Vector3.up) > slideLimit)
                sliding = true;
        }
        // However, just raycasting straight down from the center can fail when on steep slopes
        // So if the above raycast didn't catch anything, raycast down from the stored ControllerColliderHit point instead
        else {
            Physics.Raycast(contactPoint + Vector3.up, -Vector3.up, hit);
            if (Vector3.Angle(hit.normal, Vector3.up) > slideLimit)
                sliding = true;
        }

        // If we were falling, and we fell a vertical distance greater than the threshold, run a falling damage routine
        if (falling) {
            falling = false;
            if (myTransform.position.y < fallStartLevel - fallingDamageThreshold)
                FallingDamageAlert (fallStartLevel - myTransform.position.y);
        }

        // If running isn't on a toggle, then use the appropriate speed depending on whether the run button is down
        if (!toggleRun)
            speed = Input.GetButton("Run")? runSpeed : walkSpeed;

        // If sliding (and it's allowed), or if we're on an object tagged "Slide", get a vector pointing down the slope we're on
        if ( (sliding && slideWhenOverSlopeLimit) || (slideOnTaggedObjects && hit.collider.tag == "Slide") ) {
            var hitNormal = hit.normal;
            moveDirection = Vector3(hitNormal.x, -hitNormal.y, hitNormal.z);
            Vector3.OrthoNormalize (hitNormal, moveDirection);
            moveDirection *= slideSpeed;
            playerControl = false;
        }
        // Otherwise recalculate moveDirection directly from axes, adding a bit of -y to avoid bumping down inclines
        else {
            moveDirection = Vector3(inputX * inputModifyFactor, -antiBumpFactor, inputY * inputModifyFactor);
            moveDirection = myTransform.TransformDirection(moveDirection) * speed;
            playerControl = true;
        }

        // Jump! But only if the jump button has been released and player has been grounded for a given number of frames
        if (!Input.GetButton("Jump"))
            jumpTimer++;
        else if (jumpTimer >= antiBunnyHopFactor) {
            moveDirection.y = jumpSpeed;
            jumpTimer = 0;
        }
    }
    else {
        // If we stepped over a cliff or something, set the height at which we started falling
        if (!falling) {
            falling = true;
            fallStartLevel = myTransform.position.y;
        }

        // If air control is allowed, check movement but don't touch the y component
        if (airControl && playerControl) {
            moveDirection.x = inputX * speed * inputModifyFactor;
            moveDirection.z = inputY * speed * inputModifyFactor;
            moveDirection = myTransform.TransformDirection(moveDirection);
        }
    }

    // Apply gravity
    moveDirection.y -= gravity * Time.deltaTime;

    // Move the controller, and set grounded true or false depending on whether we're standing on something
    grounded = (controller.Move(moveDirection * Time.deltaTime) & CollisionFlags.Below) != 0;
}

function Update () {
    // If the run button is set to toggle, then switch between walk/run speed. (We use Update for this...
    // FixedUpdate is a poor place to use GetButtonDown, since it doesn't necessarily run every frame and can miss the event)
    if (toggleRun && grounded && Input.GetButtonDown("Run")){
        speed = (speed == walkSpeed? runSpeed : walkSpeed);
     }

          if(health>100){
           health=100;
        }
          if(health<100)
          Regen();
   Camera.main.GetComponent("ColorCorrectionEffect").rampOffsetR = (100-health)/150;
}

// Store point that we're in contact with for use in FixedUpdate if needed
function OnControllerColliderHit (hit : ControllerColliderHit) {
    contactPoint = hit.point;
}

// If falling damage occured, this is the place to do something about it. You can make the player
// have hitpoints and remove some of them based on the distance fallen, add sound effects, etc.
function FallingDamageAlert (fallDistance : float) {
    Debug.Log ("Ouch! Fell " + fallDistance + " units!");   
if(fallDistance>20)
   ApplyDamage(health-fallDistance/1.5);

}
function OnGUI () {
    GUI.Label (Rect (30, 80, 100, 30), health.ToString());

}
function Awake(){
 transform.position = respawnpoint.transform.position;
}
function ApplyDamage(points : float){
       playhurtsound();
       AddBlur();
       health-=points;
       lastHit = Time.time;
       health = Mathf.Clamp(health,0,100); // clamp health
       if(health<=0){
         audio.PlayOneShot(shadap);
         transform.position = respawnpoint.transform.position;
         health=100;
      }
    }

    function Regen(){
       // start 10 seconds after the last time you were hit
       if(Time.time-lastHit>10){
          // regain 3 hit points every second
          health+=40*Time.deltaTime;
          health = Mathf.Clamp(health,0,100); // clamp health
       }
    }

function AddBlur(){
camera.main.GetComponent("BlurEffect").enabled=true;
yield WaitForSeconds(1);
camera.main.GetComponent("BlurEffect").enabled=false;
}

function playhurtsound(){
if (Time.time > gotHitTimer) {
audio.PlayOneShot(hurtsound);
}
gotHitTimer = Time.time + hurtsound.length;

}

@script RequireComponent(CharacterController)

There you go you lazy person...