If you want to boot into Safe Mode to try and fix any issue, you need to enable it manually because it doesn't come enabled in Windows 8 by default.
To enable and use Safe Mode, follow the inline steps:
In the Safe Mode, Windows will directly boot into Desktop view. You can fix the issue your pc has here.
To disable the Safe Mode option, you need to delete the Safe Mode option from the boot options.
For Safe Mode, Windows 8 Developer Preview should be installed.You can also turn off Safe Mood if you uncheck Safe Boot check box for the Windows 8 Developer Preview.