You got lucky in a way, maybe.
Keep a heads up around the hydro drive pulley. If the belt comes off in that area it will sometimes ruin the plastic fan. Also when replacing the belt follow the owners manual instruction for such and also sometimes on the bottom of the left running board is a belt routing diagram.
You might want to replace the belt while you are under the machine.
Their is a reason the belt came off. Don't just put it back on and hope for the best. If you don't find out why IT WILL HAPPEN AGAIN.
You can keep one wheel or both wheels elevated and do a test drive watching the drive wheels. You may have to put the hydro in N to replace/re-install the belt.
Did you locate a owners manual with belt replacement instructions and a parts manual?