If you don't have an anti virus utility installed, that's your first problem. You should not run a system without a good AV running at all times.
You can download Avira or Avast for free (use google). Ditto Malware Bytes (which is NOT a replacement for an anti virus utility, it's an anti malware utility I'd like you to use to run an additional scan).
If all this is really that difficult for you I suggest you ask someone more familiar with computers to help you. This is really pretty basic stuff and you do need to have an AV installed.