I have a Craftsman 42" 6 speed manual tranny riding mower. It is about 2 years old with relatively low mileage. When I first ran it after the winter, it would not move in forward or reverse. I checked the drive belt. It looks in good shape with no apparent wear and tear.

If u can see between the mower deck and the engine check in the drive wheel spins if so the belt may have fallen off the tightening pulley u just need the loosen it and reset it, hope this helps

Mower is running but the mower will not move forward are reverse