|Could be the drive itself as there are often two lenses (one for CD, other for DVD).|
Take a look in Device Manager (shortcut is devmgmt.msc in the Run box then hit Enter). Look at DVD/CD-ROM Drives then expand out to actual drive). See if there are any errors showing, yellow question marks or red X's. Take a look in Properties to see if it shows the drive as working.
If all is OK there it might be worth getting hold of a CD/DVD lens cleaning kit. They come with a CD which has a brush, upon which you put the supplied cleaning compound.
Otherwise, from Device Manager, driver tab, uninstall CD/DVD driver and reboot. This should re-detect and re-install the driver software.
Beyond that I'm running out of ideas (except for the drive).