What do I do if some teenagers damaged my car by throwing things at it while I was driving.

If your car was damaged due to kids throwing rocks, you can file a claim with your insurance company if you have comprehensive coverage on the car.  There is a deductible for this coverage, but it is usually a lower deductible than you would have on collision coverage.  The damage would be considered vandalism which is a part of the comprehensive coverage.

You may want to get an estimate for the damages before you file a claim, just to be sure it is worth it to file the claim. It should not affect your insurance rates since it was not your fault. There are some insurance companies that do adjust the premiums for any loss, but if you have standard coverage with a reputable company it should not have any effect unless you have filed multiple claims. Claims history is kept by insurance companies and multiple claims over a short period of time can raise a red flag.