Have you tried repairing it (http://kb.gonitro.com/knowledgebase#/search/repair/000001641 ) yet?
Does it work again at least one time after you reboot your computer?
You might be able to use the last released installer from this page ( http://kb.gonitro.com/knowledgebase#/search/previous version/000001644) to update and fix Nitro 9 if the repair above didn't work.