User profile service failed the logon

Hi there. As the title suggests, I'm unable to boot my computer (Windows 7) because of this specific error. I managed to find some potential fixes online, but I've hit a wall—I can't seem to trigger Safe Mode using the F8 key. Does anyone know of an alternative way to get into it?

So, you should be able to trigger Safe Mode by tapping the F8 key right when the initial startup logo pops up—basically, start hitting F8 just before the Windows logo appears and keep at it until the Safe Mode option shows up on the screen.