Cannot mute audiosource after returing to the scene (Unity C#)

Question

Hello i have a menu scene where i have a mute button and a empty gameobject with audiosource and dontdestroyonload script attached to it. Here is the code from the gameobject.

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class Backgorund_Music_Manger : MonoBehaviour 
{
    AudioSource ads;
    public GameObject BackgroundMusic;
    bool play_sound = true;

    void Awake()
    {
        ads = GetComponent<AudioSource>();

        if(SceneManager.music == true)
        {
            Destroy(this.gameObject);
        }

        else
        {
            DontDestroyOnLoad(this.gameObject);
        }

        SceneManager.music = true;
    }

    void Update() 
    {
        if(SceneManager.currentScene == 4)
        {
            ads.volume = 0.1f;
        }
        else
        {
            ads.volume = 1f;
        }
    }

    public void stop_sound()
    {
        ads = GetComponent<AudioSource>();
        if(play_sound == true)
        {
            ads.Pause();
            play_sound = false;
        }

        else
        {
            ads.Play();
            play_sound = true;
        }
    }
}

after going back to menu the mute button stops working.

Help