How to access an external drive that's not recognized on a Mac

Most of the time, when you connect an external hard drive to your Mac’s USB port, you soon see the external drive appear on the desktop. Apple likes to ensure these are easy to find, so they also appear in the left-hand column under devices, since Mac’s treat them the same way as another computer.

However, sometimes, an external drive doesn't show up. It can be annoying, especially when you need to transfer from one to the other. This can be frustrating and slow down your day, and there can be a risk that data on the external USB pen, hard or flash drive is corrupt which means you can’t transfer what you need between devices.

Corrupt data can be one reason your Mac won't recognize an external drive, but there are other reasons too. Let’s take a look why this is happening and how you can get an external drive to appear on your Mac and get access to the data and documents.

How to troubleshoot a hidden external drive

There could be a few reasons why an external hard or flash drive isn’t making an appearance:

  1. Faulty connection. It sounds obvious, but since this relies on a wire - either a USB cable or HDMI cable - if it’s not connected properly then it won’t appear on your desktop.
  2. Faulty cable. Assuming it’s plugged in correctly, not wobbly or loose, the cable could be at fault. Try connecting the same device with a different cable.
  3. Damaged USB or flash drive port. It could be a hardware issue with the Mac. If you’ve got another port, try connecting the device to that one.
  4. Incorrectly formatted drive. Not every drive is formatted for Mac’s. It could be you are trying to connect something that only interacts with Window devices. If you’ve got a PC or laptop, it’s worth connecting it and seeing if you can access it through another device.
  5. Mac not formatted to display external drives on the desktop. It could be that your Mac already recognizes the device, but isn’t showing this on the desktop screen.If that is the case, then it will already appear in the left-hand column of the Finder menu under Devices. You should be able to access it that way, and in the Finder menu, under Preferences > General, you can tick External Drives to ensure that from now on it shows on your desktop menu.Recognize an external drive with Finder Preferences
  6. Check Apple’s Disk Utility to see if an external drive is showing up. Disk Utility is within System Preferences, or you can find it using Spotlight. If it is visible, then click the option to Mount, which should make it visible on the desktop and in the External Drives option in the Finder menu.recognize disk with Disk Utility

Unfortunately, if none of those options has worked and the external drive still isn’t visible, then it could have crashed, or be well and truly broken. There might still be a way you can recover the data on the external drive.

How to recover data from a crashed hard drive

Thankfully, there is an app for that. Disk Drill is the world’s premier data recovery software for Mac OS X. Powerful enough to retrieve long-lost, mistakenly deleted files from Macs, external hard drives and USB drives and camera cards.

An easy way to recover lost files on an external hard drive using Disk Drill

Providing you already have Pro - which you will automatically when downloading from Setapp:

  1. Connect your drive to the Mac.
  2. Quit all other applications on the Mac, especially those that may be trying to access the external drive (e.g. iPhoto, Words)
  3. Launch Disk Drill.
  4. Click on the external drive that you are trying to recover files from. If it has partitions, you will see all of them. If, however, you still don’t see any volume to the external drive then you may need to try some of the steps above again or read the Disk Drill Scanning FAQs.
  5. To avoid the external drive being accessed during the recovery process, click Extras next to the drive or drive partition or file, then select Remount Volume As Read Only. A padlock will appear, protecting the drive during the process.
  6. Now click Rebuild (or Recover) next to the file(s) you are trying to recover. Once the scan is finished - it may take some time if the files are large - a list of files will appeal. Disk Drill data recovery
  7. Next, click Mount Found Items as Disk button on the bottom-left below the scan results.
  8. Disk Drill “strongly suggest saving the files to a different drive than the one you are trying to recover files from. Saving to the same drive substantially lowers your chances of recovery.”
  9. A drive icon will appear, which once you double click will give you the option to open the files as you would do before they were lost. Drag them to another location, such as your desktop or a folder on your Mac.
  10. Open the files to ensure they have been recovered properly and safely eject the external drive.

Disk Drill does have other ways to recover lost files but assuming there aren’t complications, this method is the most effective. Disk Drill Pro recovery app is available from Setapp, along with dozens of Mac apps that will make your life easier. Never have to worry about a crashed or corrupted external drive again.