Get back your missing cd/dvd drive

Reports have filtered in that CD or DVD drives will suddenly cease to exist in XP systems. Most often this has been reported in conjunction with program installations and Windows upgrades, but it has also happened for no apparent reason. This tweak will restore the missing drives after a reboot.
First go to Start, then Run, then type regedit.
Next try to find out the following :

Registry Key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class

Key Name: {4D36E965-E325-11CE-BFC1-08002BE10318}

Value Data: [Delete All Value Data from UpperFilters and LowerFilters]

Note: Do not delete the Key or the Multi-String Values. Delete only the data values.

Exit Registry and Reboot.