I had this problem and its common. Its lost the driver and you need to go to control panel and then device manager. Click on the DVD/CDROM (which will probably have a question mark beside it telling you there is a problem). Right click on this and scan for hardware changes and it should pick it up and reinstall it. There should also be something underneath this and you right click on that and update the driver. Hopefully this will work and reinstall the drive icon on your desktop.
Good luck
Sue, May 2009