Filesystem check fail with a message saying that the superblock cannot be read

Ensure that the device listed in /etc/fstab or in the mount command actually exists. If it does not, then this error is expected, as it indicates the mount command couldn't  find the superblock. If the device does not exist, fix that problem by changing the  /etc/fstab entry or mount command, or by making the device available again.

If the device exists, run a file system check using a back up super block.There is two ways to find the backup superblock using " mkfs.ext3 and dumpe2fs "

Sample output using dumpe2fs
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# dumpe2fs /dev/sda7 | grep "Backup superblock"
dumpe2fs 1.41.14 (22-Dec-2010)
Backup superblock at 8193, Group descriptors at 8194-8195
Backup superblock at 24577, Group descriptors at 24578-24579
Backup superblock at 40961, Group descriptors at 40962-40963
Backup superblock at 57345, Group descriptors at 57346-57347
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Sample output using mkfs.ext3
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#mkfs.ext3 -n /dev/sda7 | grep -A 1 Superblock
Backup superblock at 8193, Group descriptors at 8194-8195
Backup superblock at 24577, Group descriptors at 24578-24579
Backup superblock at 40961, Group descriptors at 40962-40963
Backup superblock at 57345, Group descriptors at 57346-57347
-----------------------------------------------------------------------------------

From the above output we can make out that there is a backup superblock available in 8193 24577 ....

Now run 'e2fsck' with the backup superblock address to restore superblock

# e2fsck -b 24577 /dev/sda7