When plugged in, the external HD will run (meaning I can feel it spinning and the light is on) but the storage part of the partition will not show up :( I don't know what else to do, but I feel like there's gotta be something. I tried Disk Utility, free data recovery software and even shelled out $130 for Diskwarrior to no avail. The storage section is apparently corrupted somehow. The boot up disc is currently the only part that will mount and show anything. My external HD is partitioned so that one part is for storage and the other is a boot up disc. The next day I tried accessing my files again and could no longer view them on the desktop.
I then checked if it would show up on my desktop since it was still running Mountain Lion, which it did just fine. I recently updated my laptop to High Sierra and all of a sudden my external hard drive would not mount at all. I have a 1TB WD Passport that I use on my Macs, both laptop and desktop.