Try cleanin the contacts on the switch. Or replacing it.
You can also use a jumper when the switch is out. See if the mirrors work. Use a vom to determine which contact is the 12vdc power. jump from there to other conections.
If they still dont work. Or if there is no 12vdc. There is a breakdown in the door wiring.
Check the rubber boot that covers the wires going into the door (when you open the driver side door) My '02 had both mirrors stop working. It was a pinched wire inside the rubber boot that caused them to stop. The wire in question is (at least on my '02) a light orange with black stripe on it. I just cut the pinched area connected it back with electrical tape and they started working again. Going on 6 years since "repair" w/out any problems.