"The referenced script on this behaviour (gameobject 'player') is missing"

Hello,
Beginner Unity user here,
I am currently following the official Unity Roll A Ball tutorial, and have gotten stuck. I have copied all of the code exactly in episode 2 of the tutorial, and for some reason in the console it spits out the error “The referenced script on this behaviour (gameobject ‘player’) is missing”. I have no idea why this is happening. I have googled the problem and from it I have done the following things: Reimport All (the Assets folder), pressed F8 in Monodevelop (nothing happened) and have also re written all of the code. Yes, I do have a Rigidbody and I have checked many times and I’m like 99% sure I have everything written exactly correct. Sorry if this is a really stupid question with an easy answer, as I said I am new to Unity. PLEASE HELP!

The following is the code I have used in the script ‘Player Movement’, a script component of the sphere object ‘Player’:

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class PlayerController : MonoBehaviour {

public float speed;

private Rigidbody rb;

void Start ()
{
rb = GetComponent();
}

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

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

rb.AddForce(movement * speed);
}
}

(for some reason i cant seem to able to space things out on here, but I assure you it looks exactly the same as the tutorial.)

Unity doesn’t like when you have differences between name of script and name of class.
So, just change “Player Movement” script to “PlayerController”, following by class’s name.