Do you have two wires or one, going to each of the lights that aren't working?
If you have only one wire to the lights (pos), then the lights depend on the mounting screws for the ground (neg) connection to complete the circuit...check for a good ground...
If you have both Pos and Neg wires going to the lights, then you've probably pulled a connection loose inside the wall - a big pain to correct!
Get a cheap digital voltmeter, remove the bulb, and check both the Pos and Neg areas of the socket to see if you have Pos voltage, but no ground, or vise-a-versa...you can put the Pos probe in the center of the socket, and the Neg probe to the trailer's frame/wall to see if you have +12 volts to the socket...
You can use the Ohm meter setting to check to see if the socket base/ground is connected to the trailer's frame/wall...
Ray & Pat; Morada, CA