It sounds like the drive has failed.
I have an LG 12xSuper Multi DVD Rewriter and run Windows Me. I have been using it sucessfully for the last 6 months to burn DVD's. Today when I tried to use it to burn a DVD it informed me that there was no disk in the drive - there definitely was a disk in the drive. I thought maybe there was something wrong with the DVD so I tried a few others but got the same message. The drive doesn't seem to have a problem reading CD-R's. I have tried re-installing the software but that doesn't help. I have also tried using a CD/LD Laser Lens Cleaner and that hasn't helped either. My guess is that the DVD Rewriter is cactus but I just want to make sure that I haven't overlooked anything basic before I send it away for repairs (since it's still under warranty.