I have this issue as well. I'm thinking it's related to the Windows 10 November Update which was just released today. I could open up Start10 prior to this update.
Edit: I would like to clarify that Start10 loads whenever I log into Windows however I can't access the Start10 settings and nothing happens when I click on Start10.exe in program files.
Edit2: After several reboots everything is back to normal. Weird.