We are starting to see more of these cases today, so let's start by isolating any Updates that were installed that might have caused it. 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 not then you can Reset 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 reinstalling the Photos app from Option Two here: http://www.tenforums.com/tutorials/3175-apps-re...
You can also unhide Windows Photo viewer which is still there but hidden in Windows 10: https://www.tenforums.com/tutorials/14312-resto...
Or install Irfanviewer which is good too:
If nothing else helps you can run 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...
If you want to report this to Microsoft use the Feedback Hub app in Start Menu where developers are tasked to process consumer feedback and may interact with you. But Microsoft will not even see it here because this is a tech forums where we are mostly volunteers trying to help solve your problems.
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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