It is really dangerous to repair hard drive partitions on a damaged hard drive. There're lots of chances to waste your files, even if you utilize the best tool set and absolutely certain in all your deeds. Changes made to the corrupted partition are irrevocable; it is really easy to overwrite an important disk structure that includes vital info about your disk, files and data. First of all the substitute must be created before the start of disk recovery process.
But there're also some other ways of data recovery that are safer and simpler in usage, that don't need to have substitute and repair info. Instead of making a substitute copy of corrupted files, you may easily create a complete binary snapshot of the drive or partition being repaired, and try the fixing with different settings as many times as you require on this image instead of the real disk. That is the goal of data recovery software.