The main site administrator for our gaming team recently had a problem with his Call of Duty 4 CD Key: He couldn’t find it. There is a very simple solution for those running Windows operating systems and playing COD4 to find your CD Key.
Click on “Start” then “Run”
In the “Open” field enter “Regedit” and click on “OK”
Windows Registry Editor will open.
Expand in this order: “My Computer”, “HKEY_LOCAL_MACHINE”, “SOFTWARE”, “Activision”, and finally select “Call of Duty 4″
In the right pane you will see “codkey”. Easy enough huh?
Oh yeah, you can backup this CD key as well just in case you lose your CD case with the key AND somehow the registry gets rolled back to a previous time or gets deleted.
Right click on the “Call of Duty 4″ folder or “codkey” and select “Export”. Save this file in a safe place. If you ever need it again you can double click on the exported key and it will be imported right back into your registry.