Hi skyl1,
Sorry to hear about your problem. I have searched something for you:
- https://www.stellarinfo.com/blog/external-hard-drive-not-recognized-windows-8-1-pc/
- http://www.thewindowsclub.com/usb-device-not-recognized
- http://www.techspot.com/community/topics/troubleshoot-windows-wont-recognize-usb-hard-drive-fix-unassigned-drive-letter.122125/
The above links will help you in understanding the concept of USB or External hard drive not recognized.
Also, you can explore https://www.howtogeek.com/193798/how-to-find-drivers-for-unknown-devices-in-the-device-manager/ to know that what exactly are those Unknown devices which you have found in the Device Manager.
I hope that these links will help you out.
Good Luck!!!