Main Menu doesn't work when loading into the scene again

Unity Engine
,
1

Hello everyone, so I’m having this issue with my main menu system.
So when I start the game and I’m in my main menu, everything works fine and stuff.
Then if I load into a level and start playing it also works fine.
But then I hit escape (I have code that would load the main menu scene when I hit escape) to go back to the main menu and when I try to click anything, the mouse locks to the center of the screen.

Please help!

Main Menu script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class MainMenu : MonoBehaviour
{
    //Load Scene
    public void Play()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);
    }

    //Quit Game
    public void Quit()
    {
        Application.Quit();
        Debug.Log("The Player has Quit the game");
    }
}

Change scene by key or whatever script:

using UnityEngine;
using System.Collections;
using UnityEngine.SceneManagement;

public class Menu: MonoBehaviour {

void Update(){
if(Input.GetKeyDown(KeyCode.Escape)){
SceneManager.LoadScene("Main Menu");
}
}
}
2

UPDATE

I fixed it by adding Cursor.lockState = CursorLockMode.None;