You will need to get down and look up inside the frame and inspect the belts to make sure the rear belt hasn't come off the pulley and is jammed under the tranny pulley, or you have a seized idler pulley, and make sure the parking brake hasn't stuck in the on position. May be better to remove the deck to inspect the belts, Most likely you will need to replace them now after burning a spot on the front belt.
Always use OEM belts on MTD products, and replace both belt at the same time to remain sync in the drive system.