2002 Cadillac DeVille - Electrical issues

Short in Headlights, power locks not working

That’s a problem.

Based on the info you provided, sounds like you need a mechanic

You say there is a short in the headlight circuit, so I assume that a fuse is blowing out when they are turned on. The most likely place for a short to happen is near the lights so I would check that area out first to look for signs of trouble. Make sure there ins’t a blown fuse that is the problem with the door locks. If the fuse is okay then I would check for power getting to the door lock switches.