What can I do to recoup the money I have loss when I unknowingly bought a totaled vehicle?

I bought a vehicle about two years ago from a small dealership in Virginia. I have recently moved and made an attempt to trade the vehicle in at a large dealership to find out that the vehicle was considered a total loss back in 2011. The dealership will not accept the trade. When I purchased the vehicle I did not know the vehicle had been considered totaled let alone had been in an accident. The large dealership informed me that I should have signed some type of waiver when I bought the vehicle stating that I knew the vehicle had be salvaged. I had not. I still awe a 14-day pay off of about 15 thousand dollars.