I have an 02 B6 A4 1.8T
My windows will not go down, my radio also went out, I have a custom GPS flip out unit.
Mirrors will not work neither, can`t adjust them.
Help!!! lol

 

Personally, I'm not huge on electrical components, but it might be your battery. If your car starts, then it's not. Also maybe a fuse blew because of the GPS unit? That can happen if the GPS is directly connected into the battery and uses a lot of power.

 

What did you do before they stopped working. Good suggestion above, check all your fuses.