If you’re sure about that…

  1. Download Avast Free Antivirus: https://files.avast.com/iavs9x/avast_free_antivirus_setup.exe
  2. Follow instructions: https://www.avast.com/uninstall-utility (Run this tool for all prior installed Avast versions…!!)
  3. Reinstall Avast with the downloaded installer from point 1.
  4. Reboot.