MacOS – I’m locked out of machine as will not accept password as I shut down while using French keyboard

I hope this helps. Lockey, It looks to me like it is the very thing that you are looking for.

If you mean annoying popups such as:

X wants to use the "login" keychain. Please enter the keychain password.

you need to type your correct keychain password (usually it's the same as your login password, unless you've changed it).

It happens, because different mentioned services (see the list via: sudo launchctl list) trying to access your credentials which are encrypted and stored using Keychain (e.g. in ~/Library/Keychains/) and your login.keychain file is encrypted with different password than specified.

It's not likely you can fix it without specifying the right password, however you can try the following options (which can give you some clues):

• You may want to disable specific services from accessing your keychain, e.g.

  • sudo launchctl list
  • sudo launchctl stop <job label>

• Run Keychain Access from Utilities and invoke Keychain First Aid from the menu to verify consistency of your keychain configuration.

• Run Disk Utility and invoke Repair Disk/First aid in case there is any temporary glitch (from corruption of the file).
• Check your ~/Library/Keychains/login.keychain, such as size, the last modified date and time (which can lead you to specific changes on that date) or any potential backups in that folder or somewhere else (login.keychain).

• Try unlocking your keychain file from the command line:

  $ security unlock-keychain ~/Library/Keychains/login.keychain
  

  Using -p you can specify the password on the command line, so if you have list of potential valid password, you can write small brutal-force script.

  Try the same on older login.keychain files if you've to verify that it worked.

• Try dumping the content of keychain from the shell, e.g.

  • Try security dump-keychain command which can be used to dump the contents of a keychain.

  • Try keychaindump command which can read keychain file by hunting for unlocked keychain master keys located in the memory space of the securityd process, and uses them to decrypt keychain files.

    $ sudo ./keychaindump ~/Library/Keychains/login.keychain
    [*] Searching process 16 heap range 0x7feec8c00000-0x7feec8d00000
    [*] Searching process 16 heap range 0x7feec8d00000-0x7feec9000000
    [*] Searching process 16 heap range 0x7feeca000000-0x7feeca400000
    [*] Found 4 master key candidates
    [*] Trying to decrypt wrapping key in ~/Library/Keychains/login.keychain
    [+] Found master key: XYZ
    [+] Found wrapping key: XYZ
    

  • Try the EnCase's dumpkeychain application, which works similar as above, see: Examining Mac OS X User & System Keychains.

• Restore your ~/Library/Keychains/login.keychain file from Time Machine or somewhere else, and unlock it manually (security unlock-keychain <file>).

• In Keychain Access Preferences try Synchronize login keychain password with account, however if you're not remembering your password, it rather won't help.
• The last resort would be to do Reset Default Keychain in Keychain Access Preferences which would revert it to factory defaults and create a new empty "login" keychain and your current default keychain will be moved aside, but not deleted. That means all remembered passwords are gone unless you've some of them remembered in the web-browser, but you can start storing them from scratch.