Another way of doing this if you want to toggle sound and music both:
Personally, I would use a variable to do this. I'm not sure how you have everything organized, but I would create a global variable system that works sort of like this (let's say your variable is called "soundtoggle"- I'll explain how to code it in a minute). First, however, assume the following is what you want.
When soundtoggle = 0, all sounds are on.
When soundtoggle = 1, the game sounds are off.
When soundtoggle = 2, the music is off.
When soundtoggle = 3, both the game sounds and music are off.
Then add in logic to your event sheets that will only enable the game sounds to play if soundtoggle = 0 or 2, and only enabling music to play if soundtoggle = 0 or 1. Then (using buttons, keys, or however you want it- I'll assume you want to use keys- "m" to toggle music on and off and "s" to toggle sound on and off- for now but buttons should work similarly, I am just not that familiar with them) make an event sheet to do this (assume that "if" simply means there is a new event):
if "m" pressed:
-----if soundtoggle = 0 -------- soundtoggle = 2
-----else
-----if soundtoggle = 1 --------soundtoggle = 3
-----else
-----if soundtoggle = 2 --------soundtoggle = 0
-----else
-----if soundtoggle = 3 --------soundtoggle = 1
if "s" pressed
-----if soundtoggle = 0 --------soundtoggle = 1
-----else
-----if soundtoggle = 1 --------soundtoggle = 0
-----else
-----if soundtoggle = 2 --------soundtoggle = 3
-----else
-----if soundtoggle = 3 --------soundtoggle = 2
Does this make sense?