If it says that the disk isn't readable yet it doesn't show in the "Computer" menu (or Finder, for that matter), then:
a) It's probably not the cable - simply because if the cable was broken it would more than likely not even be able to detect it
b) It's definitely not the file format, being that you said it doesn't work on Windows or Mac
My best guess would be the volume of the HDD is corrupted and can be re-built fairly easily. Go into cmd and type in "diskpart" (without the quotation marks). Type in "list disk", then find the hard-drive (you could tell by the size, and that the space would be a format and not "primary" like your internal HDD/SSD would be.
Then, type in "select disk x", x being the number that the disk it (provided in the list by "list disk"). Then type in "list partition" and "list volume" and take screenshots and post it so I can see if the HDD is dead for good or not.