stupid radios

I put an aftermarket radio in my 1990 lumina in Feb. and I decided to install subs and I had to have a wire to turn the amp on when the radio was on. So i connected a wire to the yellow wire (constant) and put a switch on that wire. Well the wire touched metal and fried the radio but didnt blow the fuses. and i put in a new radio and it didnt even light up or anything. I put my ORIGINAL factory radio in and it works. but now when I turn the headlights on the radios light goes off and it loses its memeory everytime the car is off. WHAT DID I DO????????????

Sounds like a fried fusible-link to me.

where would that be on the cars harness??

Coming off one of the small studs at the starter.