Trent Richardson -- No One Wants to Buy My Orgy Tape

Trent Richardson's orgy tape has fallen flat ... at least in the sex tape market ... 'cause TMZ Sports has learned there have been exactly ZERO offers made to buy the X-rated footage.

We broke the story ... someone was shopping some extremely explicit video of the Indianapolis Colts running back getting down and dirty with THREE different women.

The seller was hoping the tape would score a quick payday ... but after months of shopping it around to various outlets, the person is pulling the plug on the whole plan after no one made a lucrative offer.