02 Rancher ES not shifting

Had a big ride yesterday–nine quads–to clean up a section of rugged rangeland–check drainages and fence. the ES has 7000 miles and been working flawlessly for the last three years and suddenly during the ride stopped working. I can manually shift it with the bar and the dash shows gear position no prob. So may need a battery (going on four years old) or possibly the shift motor?
Anyway she’s going in the shop.