I had this problem while trying to label a newly-created, freshly-formatted partition on a USB stick.
I formatted the file system and then tried to label it using
It gave the following error:
tune2fs: Bad magic number in super-block while trying to open
/dev/sdb1 Couldn't find valid filesystem superblock.
I transpired that I had used tune2fs while the USB partition was mounted. This corrupted the file system. I couldn't even run
fsck on it.
The solution for me was to unmount the drive, delete the partition and start all over again. This time I created the label when I created the file system, using the -L option with mke2fs:
mke2fs -t ext3 -L labelname /dev/sdb1
The drive now appears to be working and it has a label. But I've not tried tune2fs on it again. I was fortunate not to have any data on it. Running fsck, however, provided a suggestion that may have got round the problem.