Hard Drive Failure

So when I came home today, to my surprise one of my external hard drives (which had been working for more than a year) had become inaccessible and developed a "sss" sound every two seconds or so until it eventually gets quiet.

After several attempts at trying to fix this issue, I succeeded when I tried to plug it into my dad's computer. However, I was unable to transfer data to another external hard drive (one which was twice the size of the currently malfunctioned drive) as a USB error popped up saying the device was unknown.

But now once I plugged it into my own PC, it's the other way around -- with the malfunctioned drive labeled as unknown and still being able to access the functional one.

Long story short, how do I make it so that I can access both drives at once? I have a feeling it has to do with the USB ports...