Audio Systems: suddenly lost all sound, amp fuse, cherokee sport

Question
I recently installed a different changer to my 95 cherokee sport, and already have an amp to subs ing the back.  after about an hour of smug contentment, all sound suddenly was GONE.  not a crackle, snap, or pop.  However, the radio and changer both stayed on and active.. I couldn't get sound through radio stations, either, even though the radio would find stations.  There is a 7.5 amp fuse in the back of the factory head unit, but before I tear my dash off again, wondered "could that fuse blow and radio still act as if nothing's wrong?"  Please help.  

Answer
Brandy,
Please give me more details about the sound system in your Cherokee. Are the stereo and amp factory units? either way, give me the complete make and model numbers of the head unit and amp. As for the fuse (7.5amp), if the display on the stereo remains lit when the sound goes off the fuse is OK.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net