the referenced script on this behaviour is missing what does this mean and how do i fix it

hi i just started using unity and i wrote a script to make a sphere roll but every time i try to play the script an error message comes up and says “the referenced script on this behaviour is missing” how do i fix this?

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
{		
	void FixedUpdate()
	{
		float moveHorizontal = Input.GetAxis("horizontal");
		float moveVertical = Input.GetAxis ("vertical");

		Vector3 movement = new Vector3(moveHorizontal, 0.0f, moveVertical);

		rigidbody.AddForce(movement);
     }
}

Go to the inspector. Drag the script into the behaviour.

You should have a GameObject where you can see “Script: Missing” in the inspector. Go there and add your script, that fixes it.

Cheers, WRZ

This error occurs when you have a script attached to a gameobject and you deleted, moved or renamed it outside of unity. Unity can’t find the related script for the MonoBehaviour component.

To solve your error, just find the component that references this missing script and drag the right script onto the component.