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Windows has a build in registry editor tool in it.

To start it go to
start-> run
and then type 'regedit'
To run the default registry editor of windows.

It is highly advised that before making any changes to the windows registry, you back it up. To back up the registry just open the regedit tool and then go to
file-> export
You can save the whole registry set or a specific branch if required.

To restore the registry just open the file that you saved earlier.

There are many software also available to edit windows registry like the 'Registry Explorer'.