dodge ram 1500 off road no reverse

I got a 2001 ram 1500 off road edition from a guy he said that id need a new transmission but the only gear it doesn't have is reverse it goes great in every other gear and it sounds and feels like it wants to go into reverse but it goes into it just doesnt have it was wondering if anyone knows whats up?

I got a 2001 ram 1500 off road edition from a guy he said that id need a new transmission but the only gear it doesn't have is reverse it goes great in every other gear and it sounds and feels like it wants to go into reverse but it goes into it just doesnt have it was wondering if anyone knows whats up?
Take it to a reputable tranny shop to read tranny codes.