What can I do if a friend totaled my car over a year ago and we had an agreement that he would pay for my deposit but I have yet to receive anything?

 If someone damages or destroys your property either deliberately or negligently (unreasonably carelessly), you may sue them for the value of the property. If you entered into an agreement or settlement with someone who damaged your property and they don't honor it, you may sue to enforce the agreement. Either way, your recourse is to sue your friend for the money he owes you. For a larger amount, retain an attorney; for a smaller amount, represent yourself in small claims court.