I have read a lot of posts about window regulator failure and most seem to involve the window falling down. My rear driver side window is stuck in the up postion. Neither the door switch nor the drivers door master switch work. Fuse is OK. Is my problem likely to be the regulator or the motor?
Thanks

Sounds like it to me. The reason why most windows drop is because the cord comes off of the pulleys causing a loss in tension which makes the window drop. This happened to me on my front passenger window. If your window didn't drop and you don't hear any noise when you hit your switch, then I'm willing to bet that your motor went out.

it very well could be the master switch too, only way to find out would be to hard wire it or replace the switch first

I'd say switch
:cool:

I have read a lot of posts about window regulator failure and most seem to involve the window falling down. My rear driver side window is stuck in the up postion. Neither the door switch nor the drivers door master switch work. Fuse is OK. Is my problem likely to be the regulator or the motor?
Thanks

Follow up: I left the moonroof open by mistake and used the key to close it - except I turned the key the wrong way and all (yes all) the windows and roof opened. So the window problem is fixed - working perfectly. Must have been some electrical glitch.