Hi JM. I'm Greg, an installation specialist, 10 year Windows MVP, and Volunteer Moderator here to help you.
Reset and Repair Photos app at Settings > Apps > Apps & Features > Photos app > Advanced Options. Your pictures will be safe in the User Pictures folder.
If that doesn't help try re-registering the Photos app from Option Two here: http://www.tenforums.com/tutorials/3175-apps-re...
Then try uninstalling Photos app in App Settings above, restart PC, then reinstall Photos app from MS Store Hub (three dots at top right of Store app) > My Library.
If any steps cannot be performed normally then try them in 1) Safe Mode with Networking (so you have internet) or 2) Safe Mode, accessed by one of the illustrated steps in this guide: https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10. You
will need to use your password to get into Safe Mode as a PIN is not accepted.
If this was caused by Windows Updates then you can check which were installed at Settings>Update & Security>Windows Update under Installed Updates, then uninstall them from the link there, and hide with the Hide Updates tool downloaded from here:
http://download.microsoft.com/download/f/2/2/f2...
You can also use System Restore to get before the problem began, then check for Updates with the Hide Update tool and hide them:
http://home.bt.com/tech-gadgets/computing/how-t...
If nothing else helps you can try a Repair Install by installing the Media Creation Tool and choosing from it to Upgrade Now. This reinstalls Windows in about an hour while saving your files, apps and most settings, solves many problems while also bringing
it up to the latest version which you need anyway and by the most stable method.
http://windows.microsoft.com/en-us/windows-10/m....
I hope this helps. Feel free to ask back any questions and keep me posted. If you'll wait to rate whether my post helped you, I will keep working with you until it's resolved.
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