What to do if your cdrom or dvd-rom is gone:
Remove the Upperfilters and Lowerfilters values completely from the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\
Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
To do that, you need to go to Start, Run, type REGEDIT and hit enter.
Now, go to the branch indicated above, locate the Upperfilters and Lowerfilters values.
Right click each and select Delete.
Reboot.
That should fix it.