Funny, I had that issue myself this morning on my way to work. Cranked up jeep, let warm up a minute or two, hopped in, turned on radio, no sound, started nav, no sound. no sound on satellite, cd, mp3, fm, nav (prompt sound level sample).
Noticed that my EQ option was grayed out.
After turning it off and on a few times, unplugging the control box for my lockpick, turning off and on a few times, finally the sound came back on. Worked after work as well.
- Dan M