I have worked on messed up headlights for a few people............and done some amazing things.

With Some headlights, remove all metal, bulbs, etc, and heat the plastic to about 200 degrees in an oven. do about 2-3 minutes at a time. It softens the "caulk/sealant". This sounds weird, but works.

Pull the light apart and clean everything inside with clean t-shirts and windex. Let it dry off really well, put it back together and re-caulk with clear "window-door" silicone seal.

If you need any customizing done to make unusual lights/bulbs fit where
everyone says it can't be done, get back to me.-Bob