If you think you've been hacked, see this article.

For everyday virus protection, there are several good programs out there to protect you.  I recommend using a light-weight program like Windows Defender (that comes with Windows).  It's sufficient for general use. I'd also consider Avast, Avira and AVG (all free). 

More reviews here.

If you have plenty of memory and can afford a virus scan that can hog your resources (I don't think they accounted for this in their picks), check out PC Magazine's 2020 picks and price comparisons.