No startup disk on Mac, how to recover data and reinstall macOS?

Posted by Tim to Mac Data Recovery Tips on November 4th, 2020

iMac that is not booting up (macOS Catalina). The system is not seeing a startup disk, so I am not able to reinstall macOS. How should I recover data in this scenario?

1. Check Disk Utility

If there is no startup disk option when booting up your Mac, the first thing you need to do is checking Disk Utility in macOS Recovery mode.

Step 1: Turn on the Mac by pressing the Power button and hold down the COMMAND+R keys immediately until you see Apple logo.

Step 2: When you see the macOS Utilities menu, your Mac is in macOS Recovery Mode.

Step 3: Select Disk Utility and click Continue.

macOS recovery mode

Step 4: Check if your startup disk is recognized by Disk Utility.

If you see the startup disk is in Disk Utility, but Macintosh HD is not mounted, go to step 2 and recover data.

Macintosh HD not mounted

If you there is no startup disk in macOS Disk Utility, send your Mac to a Apple store for a hardware repair.

2. Recover data from the startup disk

As a professional data recovery software, M3 Data Recovery can be launched in macOS recovery mode through Terminal without the need to create a bootable drive.

Step 1: Turn on the Mac by pressing the Power button and hold down the OPTION+COMMAND+R keys immediately until you see the spinning globe.

Step 2: Connect your Mac to Internet.

Step 3: When you see the macOS Utilities menu, your Mac is in the macOS Recovery Mode.

Step 4: Open Terminal from Utilities drop-down menu.

Run Terminal in macOS Recovery mode

Step 5: Type the following command and press Return.

sh <(curl boot.m3datarecovery.com/boot.sh)

Wait a moment to launch M3 Data Recovery in macOS Recovery mode.

Step 6: After M3 Data Recovery is loaded, select the corrupted Macintosh HD and click Next to start the scan.

Mac data recovery software

If Macintosh HD is encrypted APFS file system, click "Find Lost APFS Partitions" to recover data from encrypted APFS drive.

Step 7: M3 Data Recovery is scanning the data from the unmounted Macintosh HD.

Scan lost data from corrupted drive

Step 8: After the scan completes, select the found files you expect and then click Recover to save them.

Recover lost data from failed Macintosh HD

After data recovery is successfully done, you can erase the Macintosh HD volume and then reinstall macOS.

3. Erase the Macintosh HD volume

Step 1: Start your Mac into macOS Recovery mode according to the above method.

Step 2: Select Disk Utility from macOS Utilities window and click Continue.

Step 3: In the left panel of Disk Utility, select the Macintosh HD volume you want to erase.

Step 4: Click "Erase" button on the top of Disk Utility window.

Step 5: Enther the name, select file system and partition partition scheme.

Step 6: CLick Erase.

4. Reinstall macOS

After the unmounted Macintosh HD volume is erased, now it is time to reinstall macOS.

Step 1: Start your Mac into macOS Recovery mode according to the above method.

Step 2: Select Reinstall macOS from macOS Utilities window and click Continue.

Step 3: Follow the wizard to finish the process of reinstalling macOS.

Related articles: