If your laptop has met some problems that prevent Windows booting properly, you have to start laptop to run recovery procedure from boot menu. Different laptop manufacturers offer different F keys to enter the boot menu.
In the BIOS screen, you could see there is one kind of F key provided for laptop to restore system to default settings. Press F9 and a dialog “Setup Configuration” pops up.
Choose “Yes” when it ask “Load default configuration now?”. And then wait for Windows load system default settings.
And when Windows 8 laptop encounters such functional problems, it would typically open the Automatic Repair screen, which allows you to attempt to repair the damage from there and move on to restore system to factory settings.
If all of the above couldn’t work for your laptop, you would need backup disc to restore system to early backup point.