Audio Systems: Installed Speakers but no sound, kenwood stereo, stock speakers

Question
I installed a new Kenwood stereo and ran on the stock speakers.  It worked fine until yesterday.  I upgraded the speakers to Pioneers, but there's no sound.  It was just working yesterday.

The stereo is brand new and the speakers too.

I checked fuse, checked fader/balance controls, etc.

The stereo comes on but no sound.

Ideas...Thanks,

Answer
NU,

ok your problem might be a factory amp check your vehicles specs then go from there .. also go back and double check all your speaker wiring .. and even unwire one pioneer speaker and wire directly to the head units speaker output just to make sure they function .. if they do then it could be a problem with the factory wiring so i would suggest runing new speaker wire from the head unit to the speakers so you get a good solid connection and that should fix the problem .. if you need anything else let me know

thanks