PauseMenu.cs

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

public class PauseMenu : MonoBehaviour
{
  public static bool GameIsPaused = false;

  public GameObject PauseMenuUI;

    // Update is called once per frame
    void Update() {
        if (Input.GetKeyDown(KeyCode.Escape))
        {
           if (GameIsPaused)
           {
               Resume();
           } else
           {
              Pause();
           }
        }
    }

    public void Resume()
    {
      PauseMenuUI.SetActive(false);
      Time.timeScale = 1f;
      GameIsPaused = false;
    }
    void Pause ()
    {
      PauseMenuUI.SetActive(true);
      Time.timeScale = 0f;
      GameIsPaused = true;
    }
      public void LoadMenu()
      {
         Time.timeScale = 1f;
         SceneManager.LoadScene("Menu");
      }

      public void QuitGame()
      {
         Debug.Log ("Quiting Game...");
         Application.Quit();
      }
}