So my low beams had burnt out and I replaced them but when I was done on one side the little cover inside the headlight fell off so now it works like a high beam. Anyone know how to fix this? Does the headlight assembly open?

 

I doubt it's designed to be opened up but you probably can do it. I disassembled the taillights on my 300ZX to replace the amber lens with a clear one, and did it this way (also took apart my headlights and painted the dull gray insert to match the car in glossy black). In the course of this writing, I am going to go on the assumption that this is actually possible on the Audi (assuming that the Audi has a similar design) - it may not be so proceed at your own risk.

Remove the headlight from the car - you should see a seam between the plastic of the housing and the clear of the lens. Most likely that is sealed with black tar-like glue. There's a quick and easy way to separate the halves, and a tedious, grueling, messy way. First, remove any screws that might be helping to hold the lens to the back of the housing (if there are any). The easy way is to set your oven to around 300 degrees and prop the housing in the door (with the light held between the top of the door and the front of the oven). This is close enough to melt the tar/glue, but shouldn't be close enough to damage the housings. 5-10 minutes should do it. Then you should be able to use a very small screwdriver (like a jeweler's screwdriver) to carefully pry apart the housings, picking a starting spot and working your way around. You have to go VERY slowly and carefully here - if you pry too hard, you'll crack something.

The hard way is to use WD40 (I'm talking tons of it), spraying it along the seam on the tar and using the screwdriver to pry it open. This is a pain in the ***, but it may be better if you are nervous about putting your housings up against the heat of the oven. Once you have the halves apart, you should be able to do your repair.

To put it all back together, you can heat the housings again to make the tar gooey, and then put the halves back together, and as the tar cools, it'll glue them back together. A small bead of silicone along the seam is not a bad idea once the tar is cool and dry, to make sure you don't get water in the headlights.

As I said, I've used this method on the lights of a different car, and I have no idea if it can be duplicated here, but if you want to try it out, by all means do so, just go slow, be careful, and by all means photograph and write up your work for a Tech article. I have a feeling that this can be done and that you'd be able to fix the problem - JUST GO SLOWLY AND BE CAREFUL!!!!! I can't stress this enough. Do it slow and steady and it should look great when you're done.