Start your PC, just as Windows attempts to load (spinning dots), press and hold Power Button for 5 - 10 seconds to perform a Hard Shut Down
Do this twice
On the third start Windows will boot into the Recovery Environment and from there you can access System Repair, Safe Mode, Command Prompt . . . etc.
Ggo to Troubleshoot - Advanced Options - Reset this PC
Choose to keep your files and apps, just your files or to keep nothing
Then start the Reset