Did you check the hardware device manager list? It's quite likely there's a big 'ole X over the icon representing your music player under the USB controllers section. If that's the case, delete the device and then right click on the category to Scan for Hardware Changes.
If that fails with the device returning still with an X, try right clicking on the device and select upgrade driver. Or if it doesn't reappear, unplug your music player and plug it back in. It should return then.
Have the CD with the drivers in your CD-ROM drive if possible.
