If you are unable to boot in to Windows 10 but wish to perform a system reset, you'll need to use the advanced boot menu to proceed. Please be warned that by resetting your system all 3rd party apps will be removed, however you can choose to keep personal data (i.e. Documents) during one of the steps. This is effectively a clean install which will resolve severe problems with Windows. Please make a backup before proceeding.
If you are able to boot in to Windows 10, it is much easier to reset the PC via the following method:
Without a bootable OS, you'll likely need either the recovery or installation media to boot from. If your system recognises that there is a boot problem, it may automatically show the advanced boot menu automatically after 2 failed boot attempts. As an aside, if you are within Windows 10 you can Shift+Click on the restart option to bring you to the same menu.
To begin, boot from your recovery/installation media or wait for 2 failed boot attempts. If you are using the installation media, please click next on the language selection page, then Repair your computer on the 2nd screen. Once you have done this (or you use the recovery media or wait for 2 failed boot attempts), click Troubleshoot:
Then click Reset this PC:
Now choose if you would like to keep your personal files (i.e. Documents) or remove everything:
Then choose the target operating system (Windows 10):
If you choose to remove everything you'll be prompted to choose which drives are wiped (you can play safe and limit this to the Windows drive if you are unsure, or have backups on a 2nd drive):
Finally, you'll be prompted to confirm your actions. Click Reset to being the process: