2003 Chevy Impala windows

All the windows or just one?
Either way start by checking the fuse and relay; one of the two is probably the problem if none of the windows work.
If only one window isn't working it could be a few more things:
Check the fuse and relay. If they're ok, remove a good known switch from another window and put it in place of that one. If window works then you know your switch is bad. If window still doesn't work, you may have a bad motor. Because it's expensive and time consuming to fix, I would make sure you have power at the motor with key ON and switch pressed. If you don't then something in the circuit is wrong and the motor is not the problem. If you do have power at the motor, then motor is bad.