plastic aftermarket headlights

Man, something is up w/ my headlights...
There's this unremovable film of hard water (or something else) stain on my headlights. I used window cleaner... nothing.
How can I bring it back to the way it was? :confused:
And... would anybody have any ideas as to mend a small ding on my passenger side headlight lens?

Go to Advanceauto (others should have it) and look in the polish/wax isle, and look for a little red/white can of Mothers Mag & Aluminum polish. I use this on plastic all the time, to take the wheathering out of the plastic cowls in front of the windshield on my S-10 and on the side mirror housings.

Don't ever use window cleaners that contain alcohol or you can cause tiny cracking in the plastic