My external hard drive suddenly stopped showing up in Finder or Disk Utility on my Mac. It contains important files I haven’t backed up, so I need help safely recovering the data without formatting or erasing the drive.
Don’t format it or run First Aid yet. If the drive is missing from Disk Utility, first try another cable, port, power supply, and computer, then check System Information under USB or Thunderbolt. Recovery software cannot scan a drive macOS does not detect at the hardware level. If it appears there or later mounts, make a byte-for-byte image first and scan that with Disk Drill for Mac. Clicking, beeping, or repeated disconnects means stop powering it on and use a professional recovery service.
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A drive that appears in System Information or diskutil list is a very different case from one that produces no hardware entry at all. Before assuming it is dead, open Disk Utility and choose View > Show All Devices, then run diskutil list in Terminal. Sometimes the physical disk is detected even though no volume appears in the sidebar.
If it shows up with the correct capacity, avoid mounting it repeatedly or copying files through Finder. Use another empty drive of equal or larger size and make a sector-level clone, preferably with a tool designed to handle read errors such as GNU ddrescue. Be extremely careful selecting source and destination disks. After cloning, scan the copy with Disk Drill for Mac or another recovery program, especially if the partition table or file system is damaged.
If neither System Information nor diskutil list sees it after basic connection checks, software is not the next step. The enclosure’s USB bridge may have failed while the disk itself is still readable, but opening an enclosure can complicate recovery and may expose a failing drive to more power cycles. With files that cannot be replaced, that is where I would stop experimenting and get a recovery lab to evaluate it.
Do not run First Aid on the only copy of your data, since it can change file-system metadata and make recovery harder. First test a known-good data cable, the correct power adapter, and a direct Mac connection without a hub. If the disk appears even intermittently, clone it before scanning, then use Disk Drill on the clone rather than the original. If there is still no hardware detection, stop power-cycling it and consider a recovery lab.
Cracking open the enclosure can be the exact move that kills your data. A lot of the popular WD, Seagate and similar external drives run hardware encryption on the USB bridge board, so the actual disk inside is scrambled and the key lives in that bridge. Pull the bare drive out and hook it to another adapter and you get a disk full of gibberish that even a lab struggles with. @thread759 is right that a dead bridge sometimes means a healthy disk, but before anyone reaches for a screwdriver, figure out whether your model encrypts by default. If it does, the enclosure is not disposable.
The connection checks everyone above listed are the correct starting point, no argument there. Where I’d slow down is the cloning talk. ddrescue is the right tool for a drive throwing read errors, but on a Mac it isn’t built in, you’re installing it through Homebrew or MacPorts and picking raw device paths by hand. Get source and destination backwards and you’ve overwritten your only copy. If you’re not comfortable in Terminal, that step is genuinely dangerous, and ‘be careful selecting disks’ is easier said than done at 1am when you’re stressed about lost files.
Something nobody’s asked yet is how the drive was set up. If it was formatted as APFS or was your Time Machine target, or if FileVault was ever turned on for it, that changes the recovery path completely. A clone of an encrypted volume is still encrypted, and you need the password or key to get anything back. Worth confirming before you spend effort imaging it.
Disk Drill fits fine as the scanning step once you have a clone or the drive actually mounts, and it’ll do a quick read-only look without touching the original. Just don’t expect software to do anything while the disk is invisible at the hardware level. It can’t scan what macOS can’t see.
Blunt version of my take: if these files truly can’t be replaced and the drive isn’t showing up cleanly, the money you’d spend fumbling with adapters and possibly frying it is money you could’ve put toward an evaluation. Labs are not cheap, but neither is a second failed attempt. Match your effort to how much the data is actually worth to you.