Now and again after updating a device, I get the weird issue where some of the navigation buttons are missing, the notification shade won't pull down and various other bits of the phone are broken. It's really annoying and kinda hard to fix. What's happening behind the scenes is that the phone has become 'unprovisioned', which normally needs a hard reset to resolve. That's drastic, so I've created an app that will help.
'Reprovision', free on the Google Play Store, resolves the issue by giving you the ability to re-run your devices setup wizard.
One of the weird things about the problem is that when it occurs, apps don't like to install properly from the Play Store, so it's worth keeping Reprovision installed should the problem afflict you in the future.
It's free, and hopefully this will save someone a hard reset!