Repair Boot Disk in Mac OS X with Disk Utility & Recovery HD

If you have tried to repair the boot volume before in Mac OS X before, you’ll undoubtedly have found the “Repair Disk” option is grey and unavailable within the Disk Utility tool.…

Hard drive issues. HD won't reformat or repair permissions

How to restore system files on a Mac when the hard drive is corrupted, without losing any important data - Quora

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No Disk to Install OS X or macOS? Fix Disk Not Showing Up

Learn How To Use Mac Recovery Mode Effectively – Setapp

How to Boot a Mac from an External Drive or Alternate Startup Disk

How to Verify & Repair Permissions in OS X El Capitan

Disk Utility still can't check and repair APFS volumes and containers – The Eclectic Light Company

How to Install, Reinstall, or Restore macOS Using Internet

Fixed] Mac Recovery Mode Not Working

Step-by-Step Tutorial] How to Recover Erased Hard Drive on Mac

How to restore system files on a Mac when the hard drive is corrupted, without losing any important data - Quora

SOLVED: Macintosh HD isn't visible in Disk Utility after trying to update OS X - MacBook Pro 15 Retina Display Late 2013 - iFixit

Accidentally deleted startup disk on Mac, how to fix it?

Fixed Mac Recovery Mode Not Working [Ventura/Monterey] - EaseUS