If the drive doesn't work on any computer you plug it into, the drive itself is likely dead and you'll need to replace it. If you have another computer nearby, try plugging the external disk into that to check whether it's detected.

What if the drive doesn't show up in Disk Management even after trying both of these steps? It's tough to know for certain whether the drive is bad or your computer is having a problem. Some USB hubs don't provide enough power for your external drive to function. If you've plugged the drive into a USB hub, try connecting it directly to the computer instead. See how to diagnose and fix dead USB ports if you suspect this.

Should it work in one USB port but not another, you may have a dead USB port. Unplug the drive from its current USB port and try plugging it into another port on your computer. The reason your external drive isn't detected may not lie with your device, but instead with the port you're using to connect it to your computer.