Error CS1061

Hi, i need help with my script. I have this error: Type DoorScript' does not contain a definition for index’ and no extension method index' of type DoorScript’ could be found (are you missing a using directive or an assembly reference?). I don’t know how to fix it. I search this solution on google, but it doesn’t match any solutions for this. Here’s the script:

using UnityEngine;
using System.Collections;

public class interactScript : MonoBehaviour {

public float interactDistance = 5f;
public AudioClip keyPickup;

void Update () 
{
	if(Input.GetKeyDown(KeyCode.Mouse0))
	{
		Ray ray = new Ray(transform.position, transform.forward);
		RaycastHit hit;
		if(Physics.Raycast(ray, out hit, interactDistance))
		{
			if(hit.collider.CompareTag("Door"))
			{
				DoorScript doorScript = hit.collider.transform.parent.GetComponent<DoorScript>();
				if(doorScript == null) return;
				
				if(doorScript.name == "hinge")
				{
					doorScript.ChangeDoorState();
					return;
				}

				if(Inventory.keys[doorScript.index] == true)
				{
					doorScript.ChangeDoorState();
				}
			}
			else if(hit.collider.CompareTag("Key"))
			{
				Inventory.keys[hit.collider.GetComponent<Key>().index] = true;
				AudioSource.PlayClipAtPoint(keyPickup, hit.collider.transform.position);
				Destroy(hit.collider.gameObject);
			}
			else if(hit.collider.CompareTag("NextLeveldoor"))
			{
				Application.LoadLevel(1);
			}
		}
		
	}
}

}

Please help me with this error quickly!!!

SOMEBODY HELP MEEEEE!!!