What's happened to my portable hard drive?

[CanyonRoss]

I went to use my portable hard drive, but Dolphin comes up with the following error:

"An error occurred while accessing 'Media', the system responded: The requested operation has failed: Error mounting /dev/sdh2 at /media/ross/Media: wrong fs type, bad option, bad superblock on /dev/sdh2, missing codepage or helper program, or other error"

Any ideas? It is an 8TB portable drive, the filesystem is ext4. I've tried going into partition manager and it can't even run a check, it just says error.

Thanks in advance.

[Snowhog]

What was it last plugged into successfully?

[CanyonRoss]

What was it last plugged into successfully?

It was plugged into my desktop. I have managed to fix it using testdisk, thankfully!