Contact avast and ask your money back for that horrible support.

Right now, I would say install Windows from scratch.
Who knows what else that wannabe ( not Wallaby ;D ) tech has messed up.

  • Format the drive
  • Install Windows
  • Install the latest drivers for all devices
  • Create the user accounts that/how you want
  • Install the applications that you normally are using (for all accounts)
  • Make changes in the settings if you wish to do so (e.g. other background, font type etc)
  • Put back data (if you want)
  • Create a image of the drive

With the image you can restore a system in (depending on the speed of the system) 10 - 40 minutes.
Much faster than installing Windows and everything from scratch. :wink: