I accidentally deleted the whole HKEY_LOCAL_MACHINE\Software, my computer is now unable to boot. I have tried system recovery, startup fix, previous good condition and safe mode is not working. How to fix?

  • 1
    Reinstall Windows. – DavidPostill Aug 15 at 6:50
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    Boot from another copy of OS (LiveCD for example). Find hive file in System volume information (from last savepoint) and replace "edited" hive file in system folder, than try to boot. If fail - reinstall only. – Akina Aug 15 at 6:55
up vote 2 down vote accepted

You have two chances to restore a backup copy (if one exists). In either case, you will need to have some way to modify the filesystem, whether via the recovery boot environment (command prompt), a Windows installation USB (command prompt), or a Linux Live USB.

  • If you are lucky, you may be able to simply copy the backup file at C:\Windows\System32\config\RegBack\SOFTWARE over C:\Windows\System32\config\SOFTWARE.

  • If those backups are empty (0KB size), you may need to manually restore a System Restore snapshot. Basically:

    1. From within C:\System Volume Information\_restore{GUID}\RP#\Snapshot\ (where {GUID} is a random string wrapped in braces, and # is a number identifying the restore point from 1 onwards) -- try to pick the most recent point
    2. Copy the file _REGISTRY_MACHINE_SOFTWARE over C:\Windows\System32\config\SOFTWARE
    3. You might also want to copy the others so you have a consistent snapshot rather than a newer/older SOFTWARE mismatch. From the KB:

      • Rename _REGISTRY_USER_.DEFAULT to DEFAULT
      • Rename _REGISTRY_MACHINE_SECURITY to SECURITY
      • Rename _REGISTRY_MACHINE_SOFTWARE to SOFTWARE
      • Rename _REGISTRY_MACHINE_SYSTEM to SYSTEM
      • Rename _REGISTRY_MACHINE_SAM to SAM

If none of this works, you might be stuck with a reinstall.

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