I would check a fuse first. If there is no sound it could either mean there is no power going to the motor or the motor is broken. However, usually if it is broken you hear a clicking noise or it trying to work anyway. Does the same window make noise when you press it down? What about each of the other windows? Do they go down? Do they go up? IF they don't work do you still hear the motor running?
Access to the motor will most likely be the rear side panel removed, possibly the rear seats. The pieces are bulky but it shouldn't be that hard of a job. You can do it in your driveway in an afternoon.
