Travel agent has been holding a $1,086.00 credit belonging to me for over a year and denies having it.

I purchased a vacation package that I had to cancel due to injury. The travel agent refunded the hotel money, but advised we had one year to use the airline tickets. No refund was issued. We rescheduled, and due to a difference in pricing, we were left with a $1,086.00 credit. The travel agent told us our funds were held by the airline and we had to use the funds within a year, as no money would be returned. Before the year was up, I called the airline, only to be told that they never had my money, and any credit was held by the travel agent. Their policy is when tickets are purchased by a third party, then that party becomes the owner of the booking, and they receive any credit due if there is a cancellation. They did a search and found no record of holding funds for me. I advised my travel agent, and he denies having my money. He completely ignored the last letter I sent him, which I sent certified, return receipt requested. Please advise what I can do to get my money back. Thanks.