How to fix a damaged/corrupted NTFS filesystem/partition without losing the data on it?

If you can get Ubuntu on a live CD and install NTFS-3G and NTFSProgs (in the repositories), you might be able to recover your NTFS sorrows.

I had to do this once for a friend's PC, and I followed this guy's How To. It's very helpful and it should either fix your problem OR give you more information as to what exactly is wrong (then we can work from there).

This may well do the job:

sudo ntfsfix /dev/<device name>

I had a similiar issue on one of my client's PCs. After going through multiple pieces of software such as spinrite, Windows's utilities, Linux based utilities (such as the previous answer's suggestion), HDD Regenerator was the one that found and recovered the bad sectors of the HDD in question in my case, and this HDD had almost 15% of its sectors labeled as BAD. It took approx 11 days to complete but I was able to then mount the drive and remove the user's tax, employee, and other important data.