The best tip I can give you is never load any free software (claims it will fix, repair, clean, speed up computer) into your computer, it just causes problems.
Keep all free offers and downloads OUT of your system, without exception.
Now is the time to back up your personal files onto a DVD, thumb drive, etc...
Reformat the drive, reload a fresh install of OS,
Then install a professional all in one anti virus (not a free one), reload your files from the above backup.
If you cannot backup your files, install the bad hard drive as a second drive on a working computer.
You can then usually drag your files off the damaged drive, and make a backup.
Or have a computer shop do any of the above for you...