if you plug it into ubuntu it shows up under my computer but will not mount
testdisk will not list it but the log file prints two lines concerning this drive
Warning: can’t get size for Disk /dev/sdc - 0 B - 0 sectors, sector size=512 - WD My Passport 0748
Warning: can’t get size for Disk /dev/mapper/control - 0 B - 0 sectors, sector size=512
You could at least try if it shows under parted / gparted in ubuntu. Then to see if it is partitioned correctly. If you can, try to do an image copy out of the partition and try to reformat it in order to recover your files.