is the motor making noise? might need to pull the inner panel and clean and grease the tracks. rollers are plastic and get brittle over time. you might have one broken or locked up.
If there is a forward switch from the front seat then try that, if it still dont function then Check the fuse.
If fuse is good, hook a jumper wire from a good clean ground on the door and a clean ground to the body or frame then check function of the window.
If motor still does not function then I would imagine have to get the panel removed then check that there is voltage to the switch.
If voltage is good to the switch, disconnect the plug going to the motor, then check that You have voltage each way from the switch, if not replace switch, if so then possibly bad motor.
I really dont know enough about such as this to be giving advice other than basic function tests, if I am wrong then I wiukd hooe someone with more knowledge than I would jump in and auto correct Me.