On the phone with On Star and my battery went out. When I got the car started on 2009 Cadillac Escalade EXT

I had no sound coming from non of my systems(CD player, phone, etc.

Asked by for the 2009 Cadillac Escalade EXT
I would consult your owners manual. There will be a page/s that shows you where the fuse boxes/modules are located, and what their purpose is. Check the fuses related to the sound system.