External Hard Drive not recognized at all...

Hello, I pulled the hard drive out of my previous laptop when I got a new one and have been utilizing it in an external enclosure for about a year with no issues. Recently, I turned my computer on and found that this hard drive was not being recognized by My Computer, Device Manager, or Disk Manager, however the green light showing power is still on and I can feel the vibe of the disk itself when plugged in. I have tried plugging it into other computers to no avail and have used a pen drive on the usb ports that I typically have this drive plugged into and it is recognized. I have concluded that it is the external hard drive that is the issue, but I do not know how to fix this drive and make it work once again. Any suggestions or anyone have help for me? I would greatly appreciate it! Thank you so much in advance! :)