All one can tell is that someone unbolted the drive and stole it.
But your words and description of your issue is far too short. No mention of the OS or if you still have the CDROM in the computer, but just not showing in the OS.
I can't tell if this article will help -> http://www.roxio.com/en/support/uk/ecdc/drive_recovery.jhtml
And yes, I delete both upper and lowerfilters even if I haven't used Roxio...
cd rom is missing!!! I dont know how it disappear but its gone can any body tell what happen to it and how to fix it