First thing to trouble shoot is the switch at the drivers door and the rear door itself and if that doesn't work then the window motor itself needs replacement and you can get those estimates here http://repairpal.com/estimator?car_type_id=4144 and find a repair shop here http://repairpal.com/directory?address=91504&car_brand_names=Toyota
They stop working because of lack of use. Remove the rear plastic cover and the two metal covers that cover the motor and window tracks. Tap the metal motor a few times with a hammer. Close the gate and it will start working. Buy some lithium grease and regrease everything you see that moves. Move the window up and down a few times and you should be good to go. Very common problem and 99% of the time a new motor is not required.