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 or safely recover the data without erasing it?
If the drive appears in Disk Utility but not Finder, the Mac can still see the hardware and you may be dealing with a mount or file-system problem. If it does not appear in Disk Utility at all, look first at the cable, USB port, power supply, hub, or drive enclosure. In Disk Utility, choose View > Show All Devices. If the volume is listed but gray, try Mount. You can also check Finder Settings > Sidebar and make sure external disks are enabled.
Do not erase, initialize, repartition, or copy anything onto the drive. If the files are important, I would avoid running First Aid before recovery because repairs modify the file system and can sometimes make a damaged volume harder to recover. Scan it read-only with a recovery tool such as Disk Drill for Mac, and save recovered files to a different drive. If possible, create a byte-for-byte image first and scan the image instead of repeatedly stressing the original disk.
When the drive is missing even from Disk Utility and System Information, test a different known-good cable, connect it directly without a hub, and try another Mac or enclosure. Stop powering it on if it clicks, beeps, repeatedly disconnects, or spins down. Software cannot fix a mechanical failure, and repeated attempts can reduce the chances of a professional recovery lab getting the data back.
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A spinning hard drive and an external SSD should not be treated the same once they start disappearing. With an SSD, a failed controller can make the whole device vanish instantly, and recovery software cannot scan storage that macOS never detects. With a mechanical drive, repeated spin-ups are the bigger concern, especially if it makes unusual sounds or takes a long time to appear.
Besides Disk Utility, run diskutil list in Terminal. If the drive appears there with the correct capacity, leave the original untouched and recover to another disk. If it shows the wrong size, such as 0 bytes, or keeps dropping out, stop trying software and consider a recovery lab. Swapping the USB enclosure can help when the enclosure electronics failed, but avoid doing that with drives that use hardware encryption because the original enclosure may contain the key.
After recovery, open a selection of the copied files before erasing anything. A recovery program can report success while producing damaged photos, videos, or documents, so keep the original drive unchanged until you have verified the important files and preferably made a second backup.
Nobody’s asked whether the drive actually gets enough power. That matters more than people think with bus-powered 2.5 inch drives. If yours is one of those small portable units running off a single USB cable, a marginal port or a cheap hub can starve it just enough to spin up and drop out, which looks exactly like a dead drive. Try it on a rear port of a desktop Mac, or directly into a laptop with nothing else plugged in. Desktop drives with their own power brick are a different story, and there the brick or the barrel connector fails surprisingly often, so test that before assuming the disk itself is gone.
The other thing worth knowing is whether this drive ever mounted on this Mac before. If it did and just stopped, the earlier advice about scanning read-only is solid. If it never worked here, you might be chasing a format problem instead of a failure. A drive formatted NTFS for Windows will show up in Disk Utility but won’t mount normally in Finder, and that’s not data loss at all, just macOS being picky.
I mostly agree with the read-only scanning approach, and Disk Drill is fine for that first pass since it won’t write to the source. Where I’d ease off is the byte-for-byte image suggestion. It’s good advice for a drive that’s clicking or dropping out, but for a healthy disk that just won’t mount, imaging the whole thing first is a lot of time and a second drive you might not have lying around. If diskutil list shows the full correct capacity and the drive stays connected steadily, I’d just scan it directly and skip the imaging step.
One correction on the encryption point above. It’s not only hardware-encrypted enclosures you have to worry about. If you ever turned on encryption when you formatted it in Disk Utility, or it’s a FileVault volume, swapping the enclosure or scanning it won’t help until you can unlock it with the password. No password, no recovery, and no tool changes that.
If it’s silent, spins fine, and shows the right size, you’re probably in good shape. If it’s making noise or vanishing every few seconds, stop poking at it and price out a lab before you make it worse.