300 Honda 4trac issue

earlier this summer I needed my bike to pull my stuck ztr out of a wet spot. Fired the ole girl up put it in reverse and backed up about 3 feet and it locked up. The motor runs fine and the transmission shifts. I was told the brakes might be locked up. Has anyone had this problem and what do I need to get it going again. Hunting season is around the corner and this ole man doesn't want to buy another one.