Are you missing the file path i assume. You need to identify the problem within Device Manager. this can be found through Control panel --> System --> Hardware Tab --> Device Manager. You get a new window, with information relating to all your Devices. If your driver has disapeered, (which by the way is very odd behavior), you will have a "?" in the list. Right click on the neighbouring text, and select "update driver". This will launch a wizard in which you can either connect to the web to search for a driver, or let windows search it's own driver pool on the following page, by selecting no not this time.
In most cases this should update, but thats not to say, that more likely, you haven't got a hardware problem, such as a dislodged cable or something. Let us know how you get on.
