hi, please, I'm trying to create an enemy detection script in cs and i keep getting errors (83,36) (85,78) CS1519, (73,46) CS1525, (89,27) CS8025 parsing error, please help

using UnityEngine;
using System.Collections;

public class Enemy_Detection : MonoBehaviour {

private Enemy_Master enemyMaster;
private Transform myTransform;
public Transform head;
public LayerMask playerLayer;
public LayerMask sightLayer;
private float checkRate;
private float nextCheck;
private float detectRadius = 80;
private RaycastHit hit;

void OnEnable()
{
	SetInitialReferences ();
	enemyMaster.EventEnemyDie += DisableThis;
}

void OnDisable()
{
	enemyMaster.EventEnemyDie -= DisableThis;
}

void Update ()
{
	CarryOutDetection ();
}

void SetInitialReferences()
{
	enemyMaster = GetComponent<Enemy_Master> (); 
	myTransform = transform;

	if (head == null)
	{
		head = myTransform;
	}

	checkRate = Random.Range (0.8f, 1.2f);
}

void CarryOutDetection()
{
	if(Time.time > nextCheck)
	{
		nextCheck = Time.time + checkRate;

		Collider[]colliders = Physics.OverlapSphere(myTransform.position, detectRadius, playerLayer);

		if(colliders.Lenght > 0)
		{
			foreach(Collider potentialTargetCollider in colliders)
			{
				if(potentialTargetCollider.CompareTag(GameManager_References_playerTag))
				{
					if(CanPotentialTargetBeSeen(potentialTargetCollider.transform))
					{
						break;
					}
				}
			}

			enemyMaster.CallEventEnemyLostTarget();
		}

	}

	bool CanPotentialTargetBeSeen(Transform potentialTarget)

	{
		if (Physics.Linecast (head.position, potentialTarget.position, out hit, sightLayer))
		{
			if (hit.transform == potentialTarget)
			{
				enemyMaster.CallEventEnemySetNavTarget(potentialTarget);
				return true;
			} 
			else
			{
				enemyMaster.CallEventEnemyLostTarget ();
				return false;

			}
		  } 
		else
		{
			enemyMaster.CallEventEnemyLostTarget ();
			return false;
		}
	}

	void DisableThis()
	{
		this.enabled = false;
	}
}

You had brackets in wrong spots making some of your methods be inside of other methods. Let me know if this works.

using UnityEngine;
using System.Collections;

public class Enemy_Detection : MonoBehaviour
{

    private Enemy_Master enemyMaster;
    private Transform myTransform;
    public Transform head;
    public LayerMask playerLayer;
    public LayerMask sightLayer;
    private float checkRate;
    private float nextCheck;
    private float detectRadius = 80;
    private RaycastHit hit;
    void OnEnable()
    {
        SetInitialReferences();
        enemyMaster.EventEnemyDie += DisableThis;
    }
    void OnDisable()
    {
        enemyMaster.EventEnemyDie -= DisableThis;
    }
    void Update()
    {
        CarryOutDetection();
    }
    void SetInitialReferences()
    {
        enemyMaster = GetComponent<Enemy_Master>();
        myTransform = transform;
        if (head == null)
        {
            head = myTransform;
        }
        checkRate = Random.Range(0.8f, 1.2f);
    }
    void CarryOutDetection()
    {
        if (Time.time > nextCheck)
        {
            nextCheck = Time.time + checkRate;
            Collider[] colliders = Physics.OverlapSphere(myTransform.position, detectRadius, playerLayer);
            if (colliders.Lenght > 0)
            {
                foreach (Collider potentialTargetCollider in colliders)
                {
                    if (potentialTargetCollider.CompareTag(GameManager_References_playerTag))
                    {
                        if (CanPotentialTargetBeSeen(potentialTargetCollider.transform))
                        {
                            break;
                        }
                    }
                }
                enemyMaster.CallEventEnemyLostTarget();
            }
        }
    }
        bool CanPotentialTargetBeSeen(Transform potentialTarget)
     {
            if (Physics.Linecast(head.position, potentialTarget.position, out hit, sightLayer))
            {
                if (hit.transform == potentialTarget)
                {
                    enemyMaster.CallEventEnemySetNavTarget(potentialTarget);
                    return true;
                }
                else
                {
                    enemyMaster.CallEventEnemyLostTarget();
                    return false;
                }
            }
            else
            {
                enemyMaster.CallEventEnemyLostTarget();
                return false;
            }
        }
        void DisableThis(){
            this.enabled = false;
        }
}