Make sure you backup the registry before editing.
Select Start > Run
In the Open: line type regedit and press Enter.
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
The Add/Remove Programs list is built from the keys listed beneath the Uninstall folder.
Locate the key for the program that has been uninstalled, right click the key and click Delete.
Be very careful. Once the key has been deleted it's impossible to use Add/Remove Programs to uninstall if you make an incorrect selection