What are the model and serial numbers of your machine off the back base by the wheels?
Taking a guess without knowing the model, the belt slips between the two big pulleys in the tractor section. You may have to use a long screwdrive to push the belt because of the tight fit. The belt going around the big pulley might be obstructed at one spot due to the brake - a padded arm contacting the pulley rim and back of the belt. That has to be lifted to get the belt in the pulley groove. Pull on the auger handle to lift the pulley.
Also, there may be a service manual for your model at the Toro site here:
https://homeownersolutions.toro.com/portal/server.pt?open=512&objID=214&PageID=0&cached=true&mode=2&userID=19461
This message was modified Jan 21, 2009 by trouts2