Do you hear anything at all -- like maybe a faintly click or even a rattling sort of sound. While it could be a switch, more than likely it's either the power window motor or the power window gear (which drives the regulator).
If you can take off the door panel (do you have any kind of maintenance or service manual?), you'll see what needs to be done to remove the motor and gear. I've seen some reman motors on Ebay, just be sure to read the fine print about which side the motor goes on. For sure the left and right motors are different, and I think the front and back motors are also different.
You have a 19 year old vehicle, some things are going to go sour. So even if it's only the gear that's bad (it's plastic), you might want to consider getting the entire motor and gear assembly. The motor won't last forever.
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