How to resolve DVD drive not found in Windows 7
 

In some cases your DVD drive may be missing on Windows 7, even if it's visible in the BIOS and using the standard driver.

The standard solution here is to

1. Go to run REGEDIT,
2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Class\,
3. Then delete both UpperFilters and LowerFilters in the right-hand pane (UpperFilters.bak and LowerFilters.bak entries can be ignored).

No change? Resetting the drive letter has worked for some.
Click Start, type Disk Management and choose the "Create and format hard disk partitions" link.

If your optical drive is visible here then right-click it, select Change Drive Letter and Paths, click Change and choose a new letter.

If the drive is now visible in Explorer, then repeat the process to change the drive letter back; if it's still not visible, reboot and it should appear.