i had a similar problem with the front pasenger side window some time back-it was cured by replacing the faulty window switch.
then a few days ago,the driver side window stopped working,checked the switch by doing a swap over-still did not work.
checked the fuse-it was burnt out-replaced it and window now works again.
did you check the fuse??-on my car there is one fuse for each front window in the fuse box