best antivirus for PC

Do not know how, my computer suddenly would not take, and I really do not know how to do, because many of my important files are on the inside, if not take it, then I do not work, ah later, I took the computer to be repaired, the repair shop staff that looked inside my computer said after poisoning my computer, I was thinking to how to do, then he gave me a little repair, fix , and back I installed a best antivirus for PC software, with the best antivirus for PC software, I think a computer is much faster than before, I think this best antivirus for PC software really is very easy to use , and if the early installation, then so much the better.