* By "quit working", do you mean that it just stopped appearing in Windows when you plugged it in, or did it/does it exhibit some other kind of symptom?
* Are you having problems with any other USB devices, or is it just th ethumb drive?
* Were there any errors or other indications of trouble that you noticed just before the drivestopped working? If so, give us as much detail as possible about what exactly happened.
* Does the drive work on any other computers?
* Open the Event Viewer utility in your Administrative Tools control panel and look through your System and Application logs for entries flagged with "Error" or "Warning", especially those which look like they relate to USB or drives. Double-clicking on such an entry will open a properties window with more detailed information on the error; post the details from a representative sample of some of the different error messages (please don't post duplicates of a given entry, or flood us with the entire contents of the logs).
To post the details:
In the Properties window of a given entry, click on the button with the graphic of two pieces of paper on it; the button is at the right of the window just below the up arrow/down arrow buttons. You won't see anything happen when you click the button, but it will copy all of the details to the Windows clipboard. You can then paste the details into your next post here.