LG-4250B does not recognize any inserted disk

When I insert any type of disk (software install CD, movie DVD, music CD, etc.) into the drive, nothing happens. The drive does spin and the green LED does light up, but when it all stops nothing happens. If I double-click the drive icon in Windows ‘My Computer,’ I just get the “Please insert disk into drive E:” message. It’s acting like there’s no disk in there. What could cause this?

Thanks for any help you can give me.