So, I'm trying the roll-a-ball tutorial, but when I follow his exact instructions, something breaks. any ideas?

So, I’m trying the roll-a-ball tutorial, but when I follow his exact instructions and use this script:

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {

public float speed;

private Rigidbody rb;

void Start ()
{
    rb = GetComponent<Rigidbody>();
}

void FixedUpdate ()
{
    float moveHorizontal = Input.GetAxis ("Horizontal");
    float moveVertical = Input.GetAxis ("Vertical");

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

    rb.AddForce (movement * speed);

}

}

I get an error in the console reading “The referenced script on the Behavior is missing” and when I double click it to take me to the issue, it shows the scrip with a message reading “The associated script can not be loaded. Please fix any compile errors and assign a valid script.”

What is going on, and is there any way to fix it?

Check in the script component if you have the script attached in the slot, if not add it by dragging it.