If you do not know who hit you, you should probably file a police report so that you have proof that it happened where you said it did. Then you have to file a claim with your insurance company basically as a hit and run if you don't know who hit you. You will have to pay your deductible.
If you carry physical damage coverage, contact your insurer and file a claim. Be prepared to pay a deductible, however, and allow your insurer time to try to find the at-fault party for collection. Depending on your state, you may be able to file a claim under uninured motorist coverage with varying deductibles in each state. Contact your insurer.
If you have full coverage you should get money for this accident. Since you don't know the person who is at fault your insurance will have to pay you for the damages that happened to your car. Call them and tell them what happened they will have someone come look at your car and take pictures that works for them.