How to Recover a Lost or Deleted Partition on macOS

As a Mac user, I know the feeling of panic when a partition vanishes. That sinking realization that potentially years of data, projects, or essential backups have disappeared from your drive list. It’s one of the most frustrating and common Mac issues we cover.

Whether you accidentally deleted a volume, a macOS update went sideways, or the file system simply corrupted itself, the good news is that the data is often still there. It’s usually just the map (the partition table) that’s gone missing.

This comprehensive guide will walk you through three increasingly advanced methods, starting with the safest and easiest native solution. By the time we’re done, we’ll have your drive map—and your data—back where it belongs.

STOP! The Critical Warning (the non-overwrite rule)

Before you proceed with any recovery method, this is the single most important rule you must follow to guarantee the best chance of success: Do not write any new data to the affected drive.

When macOS deletes a partition, it doesn’t erase the underlying data; it simply marks that space as available. If you install software, save a file, or even allow the system to write logs, you risk overwriting the lost data blocks, making that information permanently unrecoverable.

Immediate Action Plan:

1. Do Not Install: Do not install any recovery software onto the internal drive where the partition was lost.
2. Power Down (If possible): Shut down your Mac immediately to prevent the OS from performing routine background writes.
3. Choose a Safe Environment: You must run recovery operations from an external drive, a separate partition, or the macOS Recovery system.

Understanding the Loss: APFS Containers vs. Volumes

On modern macOS (High Sierra and later), Apple uses the Apple File System (APFS), which complicates the traditional definition of a partition.

• Partition (or Container): This is the high-level physical space on the disk. An APFS Container is equivalent to the old HFS+ partition.
• Volume: Inside a single APFS Container, you can have multiple Volumes (e.g., Macintosh HD and Macintosh HD – Data). These volumes share the container’s space, but they all depend on the container being visible. Losing the entire container is equivalent to losing the traditional partition.

Why Partitions Vanish

Cause	Description	Recovery Method Focus
Filesystem Corruption	Most common. The partition map is damaged due to a sudden power loss, improper ejection, or system crash. The partition exists but cannot be read.	Method 1: Disk Utility
Manual Deletion Error	You accidentally deleted the wrong volume or container using Disk Utility or a third-party tool.	Method 2 or 3: TestDisk / Commercial Software
macOS Update Failure	An update fails mid-installation, corrupting the partitioning scheme (often on older Core Storage volumes).	Method 2 or 3: TestDisk / Commercial Software

Method 1: Native Repair (Disk Utility in Recovery)

If your partition vanished due to corruption (the most likely scenario), macOS’s built-in Disk Utility can often repair the damage without needing complex software. This is always the safest and first step.

Requirement: You must boot into macOS Recovery Mode to ensure the disk is not in use.

1. Boot into Recovery: Shut down your Mac.
   • Apple Silicon (M-series): Press and hold the power button until you see the startup options. Select the gear icon (Options) and click Continue.
   • Intel Mac: Power on, then immediately press and hold Command (⌘) + R.
2. Open Disk Utility: From the Utilities window, select Disk Utility.
3. Show All Devices: Go to the View menu and select Show All Devices. This allows you to see the actual physical disk and the APFS Container, not just the volumes.
4. Run First Aid:
   • Select the physical disk (the top-most entry, e.g., APPLE SSD). Click First Aid and run it.
   • If that completes, select the missing APFS Container (the next level down). Click First Aid and run it again.
5. Check for Success: If First Aid reports that the drive was successfully repaired, quit Disk Utility and restart your Mac normally. Your partition should reappear.

What to know

• Not all problems are repairable by First Aid. If the partition map or APFS container metadata is severely damaged, proceed to deeper tools.
• Use macOS Recovery to ensure the disk isn’t mounted or in use.

Method 2: Advanced Free Recovery (TestDisk)

When Disk Utility fails, we move to open-source power tools. TestDisk is a powerful, free, command-line utility designed specifically to recover lost partitions and repair boot sectors.

⚠️ WARNING: Command-Line Tool

TestDisk runs in the Terminal and is non-GUI. Misuse can cause further data loss. Use extreme caution and strictly follow the on-screen prompts.

Requirement: You must install TestDisk onto a separate external drive or USB stick, as per the Non-Overwrite Rule.

1. Install Homebrew (If not installed): Homebrew is the easiest way to manage packages on Mac.

   /bin/bash -c "$(curl -fsSL [https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh](https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh))"
   

2. Install TestDisk:

   brew install testdisk
   

3. Run TestDisk:

   sudo testdisk
   

4. Select Your Drive: Use the arrow keys to select the disk that holds the lost partition and press [Proceed].
5. Specify Partition Table Type: TestDisk will auto-detect this, but for modern Mac systems, select [EFI GPT].
6. Analyze: Select [Analyze] to search for lost partitions.
7. Search: After the quick analysis, select [Quick Search] to scan the drive structure.
8. Write: If TestDisk finds the lost partition, you will see it listed. Verify the size and structure. If it looks correct, select [Write] to save the new partition table to the disk.

After writing, quit TestDisk and reboot your Mac. The partition should be mounted and accessible.

Method 3: Commercial Software Recovery

If neither Disk Utility nor TestDisk can locate or repair the partition table, the safest and easiest path forward—especially for non-technical users—is commercial recovery software. These applications use deep-scan algorithms and provide a simple graphical user interface (GUI).

The Process (Using EaseUS Data Recovery Wizard as an Example)

Crucial Step: You must download and install this software on a separate, healthy drive (either an external SSD or another Mac) to prevent data overwrite.

1. Connect Secondary Drive: Connect the external drive where the recovery software is installed to the Mac with the lost partition.
2. Run the Software: Launch the EaseUS Data Recovery Wizard application.
3. Select the Drive: The software will display all connected drives, including the one with the lost partition. The lost space will often be labeled as “Unallocated Space,” “Lost Partition,” or simply the main disk name.
4. Deep Scan: Select the affected drive and initiate the Deep Scan. This process can take many hours depending on the drive size.
5. Preview and Recover:
   • Once the scan completes, the software attempts to reconstruct the file system structure. Look for folders labeled something like Lost Files or Raw Files.
   • Preview files to ensure integrity.
   • Select the files or the entire partition structure you want to recover.
   • Save the Recovered Data to a third, separate external drive (not the source drive or the drive running the software).

This method bypasses the corrupted partition table and reads the raw data underneath, allowing you to copy files to a safe location.

Prevention: Tips to Help Prevent Lost Partitions

An ounce of prevention is worth a pound of recovery. Implement these two practices immediately to avoid this issue in the future:

1. Time Machine is Non-Negotiable: Set up and maintain an automatic, continuous Time Machine backup. If a partition is lost, you can simply wipe the physical disk and restore your data and system in one go.
2. Monitor Drive Health (S.M.A.R.T. Status): Use an application like DriveDx or run a quick check in Disk Utility to monitor the S.M.A.R.T. status (Self-Monitoring, Analysis and Reporting Technology). If the status moves from “Verified” to “Failing,” your drive is predicting imminent hardware failure, and you must back up your data immediately.

Conclusion & FAQ

Recovering a lost partition can feel daunting, but by following a disciplined, tiered approach (Repair > Free Advanced > Commercial), the chance of success is very high. Remember that in the world of data recovery, patience and not writing data are your two most powerful tools.

Frequently Asked Questions (FAQ)

Q: Can I recover a partition that was encrypted with FileVault?

A: Yes, but it significantly complicates the process. If you use commercial software (Method 3), you must provide your encryption key (or recovery key) during the scanning or mounting phase. TestDisk (Method 2) is highly unlikely to work with encrypted partitions unless you are extremely experienced.

Q: My Mac won’t boot at all. What now?

A: This reinforces the Non-Overwrite Rule. You must use a second Mac and connect the faulty Mac’s drive via Target Disk Mode (T key at startup for Intel Macs) or remove the drive and place it in an external enclosure. All recovery steps must be performed from the second, healthy machine.

Q: After recovery, should I trust the old partition?

A: If the partition was recovered successfully using TestDisk, or if data was recovered using commercial software, you should immediately format the original physical disk (Container) and create a new, healthy partition before writing the recovered data back. The corruption that caused the loss is often persistent.

Q: What if no partition or container appears at all in Disk Utility (shows as ‘Uninitialized’ or not listed)?

A: This may indicate the partition map or GPT header is damaged. At this point you’ll likely need tools that can scan the full raw disk (Method 2 or 3) or professional recovery — you should not initialise/erase the drive, as that will write a new partition map and reduce chances of recovery.

Keep learning:

• How to Partition a Hard Drive or SSD on Mac
• Best Partition Manager Apps for Mac
• How to Recover Deleted or Lost Partitions in Windows

Loved the article, share!