http://windows.microsoft.com/en-ca/windows-10/windows-10-recovery-options
or
http://home.bt.com/tech-gadgets/computing/how-to-fix-windows-10-problems-with-system-restore-11364008291943
or
http://www.thewindowsclub.com/start-menu-does-not-open-windows-10
Restore might be enabled. If so, there's usually a few points made, and it will tell you what programs you'll lose (so you can write down the names to reinstall).
You can get to the System Restore (from a restore point) from a W10 install disc if you can't do it normally through Windows.
Other:
You may have a bad drive, or bad system memory:
1) run Memtest86 free for a full pass: www.memtest86.com
2) run drive diagnostics (see manufacturer site). start with DST (drive short test). If an SSD not sure what to use.
***
a) find your way to System Restore:
- right-click desktop-> display settings-> click "gear" icon-> update and security-> backup-> more options->
-> see advanced settings-> recovery-> open system restore -> *DOES ONE EXIST? (if so click "scan for affected programs" and note).
You SHOULD make a restore point first at this point. Go back to the main System window and type in "restore point" then click on the "create a restore point" link-> make sure protection is on for your C-drive, then create a new restore point (go back to it if the other restore point doesn't help)
Other:
If you choose "Recovery" as an option instead of "Backup" then it will reinstall Windows (mostly) but you'll only be able to keep your files.
*If you have the install media, you can also choose the "UPGRADE" option which basically "upgrades" from W10 to W10. Read carefully though to ensure it won't wipe programs. It worked on Windows 7.