The switch is actually in the door locking mechanism NOT the door frame! If you open the door, and shove a screwdriver into the catch thing (where the U shaped hook which is in the frame locks onto), then you can get the door light to come on and off. I would suggest you do this on the working door first to make sure you know what position the lock has to be in.
You will need *probably* (highly likely) need to take the interior door panel off, then have a poke around to find any loose wires (which is most likely)
hope this helps
have a nice day
sanj