Without a model number, I can only give general information. I would recommend removing spark and the belt cover and make sure the auger belt is loose. If the belt is loose, try to turn the engine pulley with a pair of pliers. If the shaft will not turn, you can remove the recoil housing and see if the starter gear is jammed in the flywheel. Next, would be to remove the spark plug and then try to turn the engine. If the engine will not turn, I would suspect the engine is seized. I recommend calling a service technician to make sure, before you order a new engine or decide to buy a new snow blower.
If the oil is low or has not been changed in a long time it would cause the engine to seize.
Here is a link to set up service.
Sears Home Services
I have included a link for parts purchases; please click the following
Sears Parts Direct