when i put my vehicle into drive or reverse nothing happens

but if i put it in first, second, or third it will drive... what could be the problem. I have only had the vehicle in my possession for 18 days, it has been fine until now... drove it to work.. no problems... left work made it about a half mile, stopped at a stop sign and it wouldnt move, put it in third and drove it into a parking lot. tried shutting it off and restarting it, put it in 4x4 high, same outcome, 4x4 low same thing.