Headlights
 

Use bug spray, Repel, Off or Deet with an old sock or soft cloth, they will look like new for a few months

For many cars these days, the headlight assembly is a sealed unit with several lenses inside to make the light look brighter or stronger or wider. Replacing these can cost $500 or more each. Meanwhile, the plastic they are made of grows cloudy eventually in bright light, rather like cataracts. This makes headlights seem much dimmer.

I use a product called Micro Mesh. It’s a series of gradually finer sandpapers (well, they are on cloth, not paper, actually), running from 1500 grit to 12,000. (The 1500 is actually then equivalent of 400 grit sandpaper used for wood, and the 12,000 is so fine that it feels smooth.) You can buy it on Amazon or eBay, but not at local stores. This is used by airline mechanics to remove tiny scratches from airplane windshields and restore them to like-new visibility, so of course it works fine on headlights.

MicroMesh is waterproof and can be used wet or dry. For doing headlight covers, having a pan of water to rinse off the plastic powder sanded off is a good idea. The pieces of Micro mesh are small, and the set comes with a small foam pad to back up the Micro Mesh. Start with the coarsest piece and gradually work through every mesh until you get to the finest. (I also do stringed instrument repair, and I use Micro Mesh to put a glossy finish on hard woods like ebony and maple without having to use any varnish or lacquer and to shine up dull metals. I’ve also used it on old cracked varnish finishes to remove the top layer of varnish and leave behind the inner layer looking almost like new.) (note that a Micro Mesh kit costs about $24. There are similar kits available for a third that much, but they don’t have all of the grits, so they don’t work as well.
Amazon.com

Careful using a drill… needs to be one where you can lower the speed: I burnt the light covers on my Mercedes by using a high speed drill: had to have them replaced $$$$ ugh

I have restored several hundred headlights and I would not recommend changing the headlight unit. A simple headlight restoration will clear up the oxidation on the plastic and following up with a good quality coating that offers UV protection will help to keep the headlights clear and safe for driving at night and also look good during the day.
If your vehicle is in the sun most of the day, then even the new headlights will eventually have the same oxidation issue.

2 ideas
1 try cutter deep woods spray, be sure it has 25 % deet
2 check rockauto.com for headlight assemblies. They are usually have the best price

Sanding and polishing do the trick - BUT did you put a spray coat of protectant on the plastic lenses after getting the lenses clear again. Meguiars sells the product called "Headlight Coating" "3m has a product also" If you don't put the coating on the lense will yellow again. Both are good products.

I had mine "professionally" restored. Although they were better, I was disappointed in the results and the guy said the problem was inside as well as outside. He got the outside better......

Replace if Low $
 

A detailer once told me to replace since that would be cheaper than the labor to polish. The standard headlights on my minivan were $175 each so that was plausible until I discovered that I had upgraded factory lights which were $1000 each. I had them polished.

I had other cars where the headlight covers were individually replaceable for $100 each - excellent design.

If you do have them polished, make sure that a clear coat is applied afterwards to keep lenses clear longer.

I have used products by Novus to successfully clean and restore headlight covers and motorcycle windshields. They have a 3-step system that really works for removing oxidation and scratches from all types of plastics, including polycarbonate, acrylics, lexan, etc. Take your time, follow the directions, and you'll see results. The 3-step kit is available on Amazon for about 24 bucks.

Headlights
 

Any method is only temporary, and depending on the depth of damage how good the finish comes out. There are multiple outlets for replacements. Do not expect them to last forever either. They are made of subpar materials and will do the same thing in less than 5 years. One thing you can do is continually wax and apply uv protection to them

you can get these fixed they just clean them

There is a guy at Market of Marion that does this for a living - starting at $70 - we just had it done & love the result!

The 3M kit works well. I’ve used it on several cars. Make sure you apply the sealant after the sanding process. Otherwise headlights will yellow quickly. And I found it much easier to remove the headlights when doing the restoration. Removal allows you to do the necessary work without scratching any of the other car surfaces.

2 experiences
 

1. 2 methods exist in restoration kits. Sanding & filling. Had far superior results with filling using Meguiar's Two Step Headlight Restoration Kit (WalMart & Amazon).
2. replace it. Google - youtube for replacing headlight on your car's model. Generally fairly easy DIY. Purchase at local auto parts store.

Meguiars PlastX might be the thing you need - give it a try - slow and steady