1.
Click "Start," type "regedit" in the search bar and press "Enter." A Registry Editor window will open up.
2.
Click on the left-hand pane under "Computer." Navigate to the following folder:
HKEY_LOCAL_MACHINE \Software\Microsoft
3.
Navigate to "Office\12.0\Registration." There might be more than one folder under the "Registration" folder, but check each one for an option in the right pane named "ProductID."
4.
Double-click on "ProductID" to open the "Edit String" pop-up. The number listed in the space is your product key. Change the key here, then click "OK" to save a new key.
5.
Go back to the "Microsoft" folder root and navigate to "WindowsNT/CurrentVersion." The Windows operating system product key is accessible by double-clicking the "ProductID" option. Edit it and click "OK" to save the new product ID, but be very careful as an invalid product ID can cause your system to lock.
