You cannot fix the bad sectors. If the HDD is damaged, then you can just use a strong magnet - stroke the HDD with it a few times.
Seriously, if HDD has just 1 or 2 bad sectors, it's not a big problem, just keep in mind that is might break down when you least expect it. I had a hdd in use with few bad sectors for good few years, and it still works fine...
Though data corruption may occur.