I have Kenmore 80 series gas dryer, model 77832792. When I turn it on, it sounds like it is running but it doesn't spin. What could it be wrong with it?

The belt probably broke that turns the drum.

I checked the belt, and the belt is in tack and not broke.

If it sounds like it is running and it is not spinning that is usually the belt or the belt idler pully. If that is not it then I have no idea what is wrong. We fix them all the time and that is the usual problem.