Why would you reinstall your OS? Well maybe you are having some glitches or technical issues with your phone. Or perhaps you are trying out the Windows 8.1 Dev Preview and wish to return back to culturally acceptable Windows Phone 8? Well this recovery tool will erase everything on your phone a do a complete reinstall of Windows Phone 8.
It’s called the Nokia Recovery tool and it allows you to reinstall the latest released version of your Nokia’s Windows Phone 8 software to your phone.
http://www.nokia.com/gb-en/support/faq/?action=singleTopic&topic=FA142987
tekFranz 