This is a shot in the dark, but I would suggest trying the following:
Mount the disk with a Windows system (this may automatically repair the volume).
After that, I would suggest NOT to use an “old” filesystem that you don’t have native support for.
Use ext4 or even better, use btrfs 
You can find good Information about Btrfs in the wiki
and in
Make Backups:
(This is a standard)
but you may also look at:
If used with btrfs it is an easy way to good 1-2-3 backups of btrfs-snapper-snapshots
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