radio doesn't work

Take it out see if it's connected

Like he said take it out and see if its actuallly still connected. You might want to use A DVOM and check the fuse to see if theres actually power there. If there was an open before the fuse, or even after the fuse, the fuse would still be good but there wouldnt be any power. If there is power at the fuse, disconnect the radio and probe the power wire in for voltage with the key on obviously. If theres power at the fuse and no power at the connector then theres a problem somewhere in between. If theres power at the connector your next step would be to check the ground. If theres power AND ground then Id have to say your stereo kicked the bucket. If its stock, Ive seen many of them die so I wouldnt be surprised. If its aftermarket, some of the decks have a fuse on the back depending on what brand it is. Thatd be a good thing to check when you have the radio out.

I know you won't believe this but since you have an aftermarket Pioneer radio, believe me it's true. Pioneer and most other radio companies make a built in transformer that shuts the radio completely off if one speaker goes bad, and it don't have to blow either, just have a loose connection somewhere and the radio quits playing. If your radio will light up and come on, then this is most definitely your problem. I had the exact same problem with my Pioneer cd player, because the factory speakers after 13 years had worked themselves loose and didn't sound any good. So now my car has no radio at all, just the sweet sound of a built 5.0.