carbonel

The only answer I could give starts with a Unix bit-level copying tool called dd; I have no general expertise in the area, just memory of a recovery specialist talking about why you run fsck (the file system repair utility) ONCE and then stop, for the love of Heaven.

"spare sectors" are the sectors which don't show in the rated drive capacity; if it's a 1 TB drive, there's thereabouts of a hundred MB of spare hardware sectors that can be switched in if one of the active physical sectors goes bad. If you're getting this kind of error, the drive is out of spare sectors and can't reach its rated capacity and this is an indication of some sort of ongoing hardware problem.

One or two bad sectors can be anything, but lots-and-increasing generally mean the drive's on its way to permanent hardware death, and probably doesn't have far to go.