Electrical Problems

I need some help....I was driving when all the sudden my steering went out. Today I wanted to swap out my Pioneer deck with my friends Alpine deck. We hooked up the Alpine and it wasn't turning on, so we hook the Pioneer back up and now that doesn' work either. In addition to this, now half of the interior lights like for the heat and ac etc, and my remote keyless entry don't work. Any ideas why this is? Did I blow a fuse somewhere? Are the fuses that control the headunit related at all to interior lights and/or locks? Any help is appreciated.

Did you ground the headunit? one of my friends forgot to ground the headunit and he blew the fuses for his interior lights, headlights and a bunch of other things. check the fuses inside the car and also under the hood

ya i was playin with head unit and some loose wires touched it and blowe the fuses for the tail lights dash lights and the horn so check every fuse real good

Yea thanks guys, turned out it was the fuse....