Struggling with my pause menu and main menu

So i've just finished my game project and now I want to implement a main menu and pause menu. I decided to start with the pause menu. So I've got a pause menu code here that I thought would work but it's throwing up some errors and I'm not sure why.

Basically what I've got is a Game Object called Capsule that has a Look Object and Main Camera. I'm scripting in C# but my Mouse look script is in JS because I downloaded it as an asset.

Now I've written this pause script (following a tutorial) and attached it to the Capsule, but it gives me the errors "The type or namespace name "FPSMouseLook" could not be found. Are you missing a using directive or an assembly reference?

Help would be much appreciated!

 using UnityEngine;
 using System.Collections;
 
 public class pause : MonoBehaviour {
     
 
     public bool isPause, paused;
 
 
     // Use this for initialization
     void Start () {
 
 
         paused = false;
         Screen.lockCursor = true;
         Time.timeScale = 1;
 
 
     }
     
     // Update is called once per frame
     void Update () {
 
 
 
         if (Input.GetKeyDown (KeyCode.Escape)) {
                         paused = togglePause ();
                 }
         
 
     
     }
 
     bool togglePause()
     {
         if(Time.timeScale == 0){
             GameObject.Find("Capsule").GetComponent<FPSMouseLook>().enabled = true;
             Screen.lockCursor = true;
             Time.timeScale = 1;
             return(false);
         }
         else{
             GameObject.Find("Capsule").GetComponent<FPSMouseLook>().enabled = false;
             Screen.lockCursor = false;
             Time.timeScale = 0;
             return(true);
         }
 }
 }