fsck -N /dev/sdc1
mke2fs -n /dev/sdc1
This will output the alternate superblocks stored on your partition.
*Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208*
e2fsck -b 98304 /dev/sdc1
Reboot and see if this worked. If not try the next superblock on the list. I've had to go the third or fourth one a couple of times.
e2fsck -b 163840 /dev/sdc1
Now try the command to validate the disk again. See if you get the same messabout about bad superblocks.
fsck.ext4 -v /dev/sdc1
https://unix.stackexchange.com/questions/315063/mount-wrong-fs-type-bad-option-bad-superblock
