UNITY pause menu

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

public class PauseMenu : MonoBehaviour {

    public GameObject ui;
    public GameObject canvas;
    void Update () {
        if(Input.GetKeyDown(KeyCode.Escape)){
            Toggle();
        }
    }
    public void Toggle(){
        canvas.SetActive(false);
        ui.SetActive(!ui.activeSelf);
        if (ui.activeSelf)
        {
            Time.timeScale = 0f;
        } else
        {
            Time.timeScale = 1f;
            canvas.SetActive(true);
        }

    }
    public void Retry()
    {
        Toggle();
        SceneManager.LoadScene (SceneManager.GetActiveScene().buildIndex);
    }
    public void Menu()
    {
        SceneManager.LoadScene("MainMenu");
    }
}