I need some help please

my computer must have gotten a virus and now I boot it up and every word is no longer letters it is symbols, I can't log in or do anything on it, how to I factory reset my computer, it's a windows 8.1? Please help me.

Just format everything and reinstall.

How would I go about doing that?

Depending on your computer there should be options available at start up F8, F10, F12. Look for factory refresh options and ABSOLUTELY make sure that you find the option to format the install drive. It should present itself when you're selecting which drive to install windows. Don't start the process until you find that option or the virus won't be erased.

It has boot options (F12) and setup (F2), I can't seem to find the reboot