If the deck doesn't turn on, check the fuse (usually located in the back of the deck itself) If that fuse is good, check the fusebox for blown fuses going to the radio. It's a possibility that the horn fuse has blown as well. (this happens frequently on my fathers 02 silverado)
If that fuse is okay, use a basic voltmeter to verify the following wires are good on the deck: 12v+ power, ground, and turn on lead. If your fuses, ground and power/rem wires are good, then there's somthing up with your head unit.