Mike,
It would help if you could tell the community what trailer you have and the year of manufacture. There may be others who
know more about your specific model.
I would check the 12 volt fuses first. Don't assume they are good because they visually look okay. Check them with an ohm meter or measure both sides of the fuse with a volt meter to insure 12 volts on both sides.
If you don't find anything there, you may have a bad connection somewhere to the circuit that feeds those lights. Then it becomes a bit of a hunting expedition to find the bad connection.