Can't access data in Public folder


I really think something bad happened in my device.

Here’s what I get with SSH :

~ # df -h
Filesystem                Size      Used      Available     Use%     Mounted on
/dev/md0                   1.8G    120.6M            1.6G        7%        /
/dev/md3               949.6M      17.5M       883.8M        2%        /var
/dev/md2                    1.8T    327.3G            1.5T      18%        /DataVolume
/dev/ram0                61.9M       20.0k          61.9M       0%        /mnt/ram
/dev/md2                    1.8T    327.3G             1.5T      18%       /shares/Download

The Public folder (where all my data is) is no longer mounted but the 327gig still showing up. What the …

If I list files on DataVolume, I get this :

/DataVolume # ls
exils: ./Public: Input/output error
Download   _torrent_   jewab

Anyone knows what wrong with the Public folder ? Why the input/output error ? I’m not very familiar with linux.