main menu not loading level 1 please help beginner here

Hello! I am trying to figure this out because it was working and now that I am done with my game it wont play level 1 :( I get this error "ArgumentException: Input Button Submit is not setup."

I will include my main menu script:

 using UnityEngine.SceneManagement;
 using UnityEngine;
 using System.Collections;
 
 
 public class MainMenu : MonoBehaviour {
     public GUISkin skin;
 
     void OnGUI()
     {
         GUI.skin = skin;
         GUI.Label (new Rect (10,10, 400,45), "Go Home");
         if (PlayerPrefs.GetInt("Level Completed") > 0)
         {
             if (GUI.Button(new Rect(10, 60, 100, 45), "Play"))
             {
                 SceneManager.LoadScene(PlayerPrefs.GetInt("Level Completed"));
                 SceneManager.LoadScene(0);
             }
         }
         if (GUI.Button(new Rect(10, 60, 100, 45), "Play"))
             {
                 PlayerPrefs.SetInt("Level Completed", 0);
                 SceneManager.LoadScene(0);
             }
 
         if (GUI.Button (new Rect (10, 210, 100, 45), "Quit"))
             {
                 Application.Quit();
             }
     }
 }

THIS IS MY GAME MANAGER

 using UnityEngine;
 using System.Collections;
 using UnityEngine.SceneManagement;
 
 public class GameManager : MonoBehaviour
 {
     // Count
     public int currentScore;
     public int highscore;
     public int token;
     public int tokenCount;
     private int totalTokenCount;
     public int currentLevel = 0;
     public int unlockedLevel;
 
     //Timer Variables
     public Rect timerRect;
     public Color warningColorTimer;
     public Color defaultColorTimer;
     public float startTime;
     private string currentTime;
 
     //References
     public GameObject tokenParent;
 
     void Update()
     {
         startTime -= Time.deltaTime;
         currentTime = string.Format("{0:0.0}", startTime);
         if (startTime <= 0)
         {
             startTime = 0;
             Destroy(gameObject);
             SceneManager.LoadScene(0);
         }
 
     }
 
     void Start()
     {
         totalTokenCount = tokenParent.transform.childCount;
         if (PlayerPrefs.GetInt("Level Completed") > 0)
         {
             currentLevel = PlayerPrefs.GetInt("Level Completed");
         } else {
             currentLevel = 0;
         }
         //DontDestroyOnLoad(gameObject);
     }
 
 
     public void CompleteLevel()
     {
         if (currentLevel < 3)
 
         {
             currentLevel += 3;
             PlayerPrefs.SetInt("Level Completed", currentLevel);
             PlayerPrefs.SetInt("Level " + currentLevel.ToString() + " score ", currentScore);
             SceneManager.LoadScene(currentLevel);
         } else {
 
             print("You Win!");
         }
     }
 
     public void AddToken()
     {
         tokenCount += 1;
     }
     
     //GUI SKI
     public GUISkin skin;
 
     private void OnGUI()
     {
         GUI.skin = skin;
         if (startTime < 5f)
         {
             skin.GetStyle("Timer").normal.textColor = warningColorTimer;
         } else {
             skin.GetStyle("Timer").normal.textColor = defaultColorTimer;
         }
 
         GUI.Label(timerRect, currentTime, skin.GetStyle ("Timer"));
         GUI.Label(new Rect(45, 100, 200, 200), tokenCount.ToString() + "/" + totalTokenCount.ToString()); 
                  
     }
 }