My external hard drive suddenly stopped showing up on my Mac, including in Finder. It contains important files I need to recover. What steps can I take to access the drive without losing or overwriting my data?
Disconnect the drive for now and avoid Erase, Initialize, formatting, or repeated First Aid attempts. Those actions can change the file system and make recovery harder. Reconnect it with a different cable and port, preferably without a hub, then check Disk Utility with View > Show All Devices. Check System Information under USB or Thunderbolt too.
If the physical drive appears there but the volume will not mount, make a byte-for-byte image or clone to another drive before attempting repairs. Scan the image or original with a recovery tool such as Disk Drill for Mac, and save recovered files to a separate disk. Recovery software cannot help if macOS does not detect the hardware at all.
If it clicks, beeps, repeatedly disconnects, or fails to spin up, stop powering it on. That points to a hardware problem, and continued attempts can worsen the damage. For truly irreplaceable files, a professional recovery lab is safer than experimenting with repairs.
Open Terminal and run diskutil list before installing recovery software or attempting repairs. If the drive and expected partition appear there, Finder may simply be hiding it, so check Finder > Settings > General and Sidebar for “External disks.” If it shows the wrong capacity, has no partition, or keeps disappearing from the list, stop reconnecting it and follow @just_raven’s imaging or recovery-lab advice.
If the drive is physically failing, software may not recover everything. @just_raven’s diskutil list check is the right starting point, but first try a different cable, port, and powered enclosure since insufficient power can make a healthy drive vanish. If macOS detects it consistently, scan it with Disk Drill and save recovered files to a different drive. Don’t initialize, erase, reformat, or run First Aid on the original until the important data is copied or the drive has been imaged.
Cloning a failing drive with Disk Utility’s imaging isn’t the safe move it gets treated as here. A plain image or clone reads straight through, and the moment it hits bad sectors it can stall, retry the same spot over and over, and put more wear on a drive that’s already struggling. If you suspect physical trouble, use ddrescue instead. It grabs the healthy areas first, skips the bad ones, and only comes back for retries later, which is much gentler on a dying disk. You can install it through Homebrew and point it at the raw device from Terminal.
@lucid_bit’s diskutil list step is the right gate, and I’d lean on it before anything else. If the drive shows up with the correct size but won’t mount, you’re in decent shape and software has something to work with. If it flickers in and out of the list or reports garbage capacity, that’s your sign to stop reconnecting and image it once, carefully, rather than poking at it.
Disk Drill fits fine once you’ve got a good image to scan, since you can throw it at the copy instead of the original and lose nothing if a scan goes sideways. Just don’t expect it to pull a rabbit out of a hat if the hardware is the problem. No recovery app reads sectors the drive itself can’t hand over. At that point a lab is the honest answer, annoying price and all.