Most files lost from an external hard drive can be found again, as long as the drive still shows up in Disk Utility and nothing new has been written over them. Spinning hard drives don’t erase deleted data on their own. They just mark the space as free. A drive that won’t mount usually has a damaged file system, not missing files.
What matters is doing things in the right order: copies first, then reading the drive, and only then anything that writes to it, such as First Aid or an erase. Find your situation below.
If you deleted files from the drive
- Plug the drive in and check the Trash. Files you trash from an external drive stay on that drive in a hidden Trash folder, and only show in the Trash in your Dock while it’s connected. Select a file and choose File ▸ Put Back.
- Look for a copy. Time Machine, iCloud Drive, the Mac the files came from, the camera or phone that made them.
- Stop saving to the drive. Don’t copy anything onto it, and if it’s a Time Machine disk, turn backups off in System Settings ▸ General ▸ Time Machine until you’re done.
- Scan it. See the steps below.
If the drive won’t mount
When an external drive doesn’t appear in Finder, the problem is often the connection rather than the drive. Check these first:
- Use a different cable and a different port, and plug straight into the Mac instead of a hub.
- Desktop drives (the larger 3.5-inch kind) need their own power adapter. Make sure it’s plugged in and the drive spins up.
- In Finder, open Finder ▸ Settings ▸ General and make sure External disks is checked, so a mounted drive actually shows on the desktop.
Then open Disk Utility (in Applications ▸ Utilities) and choose View ▸ Show All Devices.
- The drive and its volume are listed but grayed out. Select the volume and click Mount in the toolbar. If it mounts, copy your files off now.
- It won’t mount. Scan the drive with a recovery app before you run First Aid. First Aid writes to the drive to repair it, and on a damaged drive that can make matters worse. Once your files are safe, try First Aid.
- Your Mac says “The disk you attached was not readable by this computer.” Click Ignore. Initialize leads to erasing the drive.
- The drive isn’t listed at all. macOS can’t see it, so no recovery app can read it either, Reco included. Try another Mac and another cable. If it still doesn’t appear, it needs a data recovery lab.
A drive formatted on Windows as NTFS mounts on a Mac as read-only. That’s normal and not a fault: you can copy files off it, just not onto it.
If the drive is clicking, slow or disconnecting
Clicking, beeping, grinding, long freezes and drives that drop off mid-copy are signs of a failing drive. A failing drive can get worse with every hour it runs, so the goal is to read it once, carefully.
- Check what the drive says about itself. Reco’s Drive Check-up shows the drive’s own health report (SMART) in plain words. Not every USB enclosure passes this report on, so a missing report doesn’t mean the drive is fine. See how to check a drive’s health.
- Copy it before you scan it. Reco’s Copy first copies the drive to a disk image on another drive. You can stop and pick up where you left off. Then scan the image, not the drive.
- Don’t run First Aid or repeated scans on a drive that’s clicking. They make the drive read the same areas again and again.
If the drive makes a loud repeated click and doesn’t show up, or it was dropped, turn it off. That’s a job for a lab with a clean room, and powering it on again can damage the disk surface.
Scan the drive with Reco
Reco is free, with no limit on how much you recover. It opens the drive read-only and never writes to, repairs or formats it.
- Choose the drive in Reco’s list, or open the disk image you made with Copy first. If the drive has several partitions or APFS volumes, each one is listed, so you can scan just the one you need.
- Run a deep scan. It reads every part of the drive at the drive’s own speed, which for a large hard drive means hours. The time left is measured, not guessed. You can pause, quit, unplug or restart, and Reco continues where it stopped.
- Review. Photos and videos show as thumbnails. Each file shows how intact it is. Original names and folders come back where the drive still remembers them. Show each file once hides duplicate copies, which is handy on drives that held backups.
- Recover to a different drive, with enough free space for what you’re saving. Reco won’t save onto the drive it’s reading. A recovery report with checksums is saved with the files.
macOS asks for your password or Full Disk Access first, because reading a whole drive is protected. Reco explains which one it needs and uses it only to read. It reads APFS, Mac OS Extended (HFS+), exFAT, FAT32 and NTFS.
What usually comes back
| Situation | Chances |
|---|---|
| Files deleted from a hard drive, little saved since | Good |
| Drive won’t mount, but shows in Disk Utility | Usually good |
| Drive erased or reformatted by mistake | Usually good on a hard drive. See formatted drives. |
| Drive failing but still readable | Partial to good, if you copy it first |
| External SSD | Varies with TRIM. See TRIM explained. |
| Drive not seen by macOS, or physically damaged | Needs a lab |
No app can bring back data that’s been overwritten, and no app can promise a result. A good scan tells you honestly what’s there.
So it doesn’t happen again
- Keep important files in two places. An external drive that holds the only copy is a backup waiting to fail.
- Eject the drive before you unplug it, and don’t move a desktop drive while it’s running.
- Check its health now and then with Drive Check-up, and replace a drive that reports problems.
Questions
Can I recover deleted files from an external hard drive on a Mac?
Usually, if little has been saved to the drive since. Spinning hard drives don’t erase deleted data until it’s overwritten. Check the Trash with the drive plugged in, then scan the drive with a recovery app and save the files to a different drive.
How do I get files off an external hard drive that won’t mount?
Open Disk Utility, choose View ▸ Show All Devices, and see whether the drive is listed. If it is, try Mount, and if that fails, scan it with a recovery app before running First Aid or erasing it. If it isn’t listed at all, no software can read it.
Should I run First Aid before recovering files?
If the files matter, recover them first. First Aid repairs a drive by writing to it, which is usually fine but can make things worse on a drive that’s badly damaged or failing.
My external hard drive is clicking. What should I do?
Stop using it. Clicking usually means a mechanical fault, and every hour it runs can make it worse. If it still shows up, copy it once to a disk image and scan the copy. If it doesn’t, or the files are irreplaceable, take it to a data recovery lab.
Is recovery different for an external SSD?
It can be. Some external SSDs use TRIM, which erases deleted data soon after you delete it. See TRIM explained.