Radio problems

I have a 91 gmc sierra, one day i got in it and the radio didn't work. i checked the fuse it was ok, a week or so later i tried to hook up a power inverter ,truck was running when i was putting it in, before i even got it in the digital clock and all the interior light quit working!
I don't know if there is a short or what , but it really starting to suck w/out a radio. please give me any ideas you have to fix it :confused: