Before you worry about restoring your computer, see if you can clean up the trouble. From another computer, download MalwareBytes' Anti-Malware
(the free version) and put it on a flash drive. Install it in your computer and run a full scan. This is a very effective program, updated continuously as new bad software comes along, and is the first thing I try when someone calls me for help.
If MBAM doesn't fix it, you can try another program called ComboFix. You can get it here
. (A tutorial and download link is here
at BleepingComputer.com, a good site for getting information and help on computer troubles.)
If you need to restore your computer (you said "reboot", but I assume you mean "restore", which puts the original factory software image back on), you'll need the manufacturer's recovery disc or discs. Older computers usually came with a set, but most newer computers no longer have the discs included. Since CD or DVD writers are standard equipment, the manufacturer provides a utility program that lets you make your own recovery discs after you set up the computer. This is a step many people ignore, however. If you don't have a recovery set, you might be able to purchase one from the manufacturer, or you can install a fresh copy of Windows yourself.
Try MBAM first, then ComboFix if necessary. Chances are very good that this will get your computer going again. Good luck, and thanks for using Fixya!