While you can get yourself any number of programs, put them on a disk or USB drive, connect to the computer and format the hard drive. Which would clean anything you had on it off. Personally I would format it a few times, but that is me.
However that can't say if it will be worth fixing or not. Without knowing what was wrong with it in the first place, and what steps you already took to fix it, there is no way to answer that part of your inquiry.