I want my character to fall like ragdoll when he’s not standing on floor, like if i just walk from high ledge my character will turn into a ragdoll untill it hits the floor again. I need this so much please help guys 
Fairly easy, just check if your player is in the air (If your character is able to jump, you need to take that into your if-statement).
You need to create a ragdoll of your rigged model and create a prefab from it. Then use just check if your player is falling or just jumping. If he is falling, instantiate the ragdoll prefab and hide the player game object.