Some people upgrading to Windows 7 will not be able to see their DVD drive after the fact. There is an easy fix for this.
To get this Windows 7 issue resolved, navigate to REGEDIT, and browse HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\, and delete both UpperFilters and LowerFilters in the right-hand pane.
On the other hand you can reset the drive letter. Click Start, type Disk Management and choose the “Create and format hard disk partitions” link. Navigate to your optical drive and right click it. From here change the drive letter path and apply the new chosen one. Even the drive letter change can be managed form the Explorer. If you still are in vain to locate the hard drive, then reboot the system and you would be able to obtain your drive.