Some infection just slipped in my pc and now it just keeps on multiplying. i tri

some infection just slipped in my pc and now it just keeps on multiplying. i tried to remove it from antivirus but that also didn't worked. instead the antivirus itself got corrupted. and then i tried to correct the problem through safe mode but i just couldn't get into it. every time i chose safe mode to start with, my computer would just reboot again . Plzzzzz help me with this. I have important files that i want to save on the hdd.