Macworld Normally when you plug in an external hard drive to your Mac’s USB port you will see it appear on the desktop (aka mount on the desktop). You can also see it in the Finder in the left column under Locations (or Devices in older versions of macOS). If the drive is not showing up on your Mac chances are it has not been formatted correctly, has been corrupted, or is faulty. Alternatively, you may have set a password for the drive that you need to enter before it will connect. We show you how to work out whether the reason the external drive is not mounting on your Mac up is due to a prob…