car wont start!!

[pablla4]

i just removed the aftermarket dvd unit out of my 06 hummer h3 and installed the factory one because i was suppose to trade it in today but now the car wont start. i tried to get it towed but the it wont shift into neutral! i dont know what to do anyone have any ideas? there is also a black n red wire coming from the steering wheel, and a black/white wire and blue wire under the dash that have been disconnected by my brother and he dont remeber what was hooked up to it. there is also a black wire comin from the computer that the installer has that is not connected under the dash.