Many time i have observed 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.Just follow the following steps :-
[Start] [Run] [Regedit]
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 For more details just subscribe in the email.