Ironically, this just happened to me also Ramper! It does appear to me that what Hobkirk says may be the issue, I inadvertently may have have disconnected something.
In my situation, the drive wheel isn't making any contact w/ the rubber wheel, I push the drive handle down, follow the mechanisms associated w/ it and it doesn't seem to engaging the drivewheel up against the rubber wheel (which doesn't appear to be worn too much itself)..froze up..or something else. I will keep you posted If I can determine the cause. Luckily my old trusted Snapper I keep as a back up ran like a champ, as we have gotten some snow the last couple of days here in CNY.