Formatting a drive on a Mac usually doesn’t wipe your files. A normal Erase in Disk Utility writes a new, empty file system, which is the drive’s index of what’s stored where. The photos, videos and documents themselves stay on the drive until something new is written over them. On an SD card, USB stick or external hard drive, a recovery app can often find most of them again.
Two kinds of erase can’t be undone: one that writes over every part of the drive, and one on an SSD that macOS trims. The table below shows which one you’re likely facing. Whichever it is, stop using the drive now.
First: stop writing to the drive
Everything you save to the drive from now on can land on top of what you lost. So:
- Don’t copy files onto it, and don’t take new photos or video on a card you formatted.
- If you erased the drive to use it for Time Machine, stop the backups: in System Settings ▸ General ▸ Time Machine, select the drive and remove it.
- If your Mac shows “The disk you attached was not readable by this computer,” click Ignore, not Initialize. Initialize erases the drive.
- If a camera offers to format the card, say no.
Which kind of erase was it?
| What happened | Chances | Why |
|---|---|---|
| Erase in Disk Utility (the default) on a hard drive, SD card or USB stick | Good | Only the file system is rewritten. The old data is still there. |
| Reformatted to a different format, such as exFAT to APFS | Good | The new file system takes up a small part of the drive. The rest still holds the old data. |
| Card formatted in a camera (normal format) | Usually good | A normal in-camera format also just rewrites the file system. |
| Erase or reformat of an SSD that macOS trims (your Mac’s built-in disk, most NVMe drives on Thunderbolt or USB4 formatted as APFS) | Low | The SSD clears the space it’s told is free, and an erase frees all of it. |
An erase that writes zeros over the drive: Disk Utility’s Security Options, diskutil zeroDisk or secureErase, a full (not quick) format in Windows, a camera’s “low-level format” | None | Every part of the drive has been overwritten. |
| A Mac reset with Erase All Content and Settings | None | The Mac’s own disk is erased by destroying its encryption keys. |
Disk Utility only offers Security Options for some drives, and never for SSDs, so a plain Erase is by far the most common case. If you’re not sure what was done, scanning the drive will tell you: a drive that was overwritten simply comes back empty.
Look for copies first
Before you scan, think about where else the files might be. A Time Machine backup, iCloud Drive, the phone or camera that took the photos, a shared folder, an old laptop, an email you sent. Restoring from a copy is quicker and comes back with every name and folder intact.
Scan the formatted drive
If there’s no copy, the files have to be found on the drive itself. A recovery app reads every part of the drive, not just what the new file system lists, and rebuilds the files it finds. With Reco, which is free:
- Install Reco on your Mac, not on the formatted drive.
- Choose the drive. Plug it in and select it in Reco’s list. It may show its new name. If it has several partitions or APFS volumes, each one is listed, so you can scan just one.
- Run a deep scan. It reads the whole drive at the drive’s own speed. That’s minutes for a small card and hours for a large hard drive, and the time left is measured, not guessed. You can pause, quit or unplug, and Reco continues where it stopped.
- Review what it found. Photos and videos show as thumbnails. Each file shows how intact it is, and damaged files are marked as damaged. After a format, many files come back without their original names and folders. Reco restores names and folders where the drive still remembers them.
- Recover to a different drive. Reco won’t save onto the drive it’s reading and never writes to it. A recovery report with checksums is saved alongside the files.
macOS will ask for your password or for Full Disk Access, because reading a whole drive is something it protects. Reco explains which one it needs, and uses it only to read.
Reco reads APFS, Mac OS Extended (HFS+), exFAT, FAT32 and NTFS drives, and finds photos (including camera RAW), videos and documents. For camera cards, see SD card recovery on Mac.
If the drive won’t mount or asks to be initialized
Sometimes a drive wasn’t formatted on purpose. It just stopped mounting, and macOS offers to initialize it. Don’t. Instead:
- Open Disk Utility (in Applications ▸ Utilities) and choose View ▸ Show All Devices.
- If the drive is listed, recover what you need before you run First Aid. First Aid repairs the drive by writing to it, and an erase is always the last resort.
- If the drive isn’t listed at all, try another cable and port. If it still doesn’t appear, macOS can’t see it, so Reco can’t either. A drive in that state needs a data recovery lab.
If the drive clicks, disconnects, or makes Finder hang, use Reco’s Copy first to copy it to a disk image once, then scan the copy instead of the drive.
Once your files are safe
- Check the important files open properly before you reuse the drive.
- Then format the drive again for its new job. Format camera cards in the camera.
- If you’re formatting a drive to give away or sell, a normal erase isn’t enough, for the same reason this guide works. See how to securely erase a drive.
Questions
Can I recover files after formatting a drive on a Mac?
Often, yes. A normal erase in Disk Utility only writes a new, empty file system, so on an SD card, USB stick or hard drive the old data stays until something new is saved over it. Stop using the drive and scan it with a recovery app.
Does reformatting a drive delete everything?
It removes the list of files, not the files themselves, unless the format writes over the whole drive (a zero-fill or secure erase) or the drive is an SSD that macOS trims. Those two can’t be undone.
Can I recover files after erasing an SSD in Disk Utility?
Usually not. When macOS trims an SSD, the drive itself clears the space it was told is free, and an erase frees all of it. SSDs that macOS doesn’t trim, and drives formatted as exFAT, have better chances. See TRIM explained.
My Mac says the disk is not readable. Should I click Initialize?
Not if you want the files. Initialize opens Disk Utility to erase the drive. Click Ignore, then try to recover the files before anything else touches the drive.
Will Reco write to or repair the formatted drive?
No. Reco opens the drive read-only and never writes to, repairs or formats it. It saves recovered files to a different drive.