Using chkfsys
The chkfsys utility is your principal tool for checking and restoring a potentially damaged filesystem. It can identify and correct a host of minor problems as well as verify the integrity of the disk system as a whole.
Recovering from a bad block in the middle of a file
Hard disks occasionally develop bad blocks as they age. In some cases, you might be able to recover most or even all the data in a file containing a bad block.