There is not simple easy fix. You can check any plugs that go
from that to the wiring hardness that goes back to the engine.
You're just going to need to trace it down which will take some time.
If its not going in either direction but works from the back
you have a bad connection (most likely power)

You can always see if the switch is just bad by jumpering the
connections
but if you unsure about your electrical skills, leave it up to a good
mechanic.

Tom