Cannot reset password using Apple ID I got quite the headscratcher here...
I'm in a password reset loop. I have been tasked with &quot;fixing&quot; my wife's MacBook. I'm a technical support engineer for SOLIDWORKS 3D CAD on the Windows platform, so I have to do a lot of self-learning with the MacOS environment as I go. I've exhausted everything I could find mentioned online and would be very appreciative of some insight from more experienced users.
THE GOAL

Access the HD to recover important documents and pictures.

THE SITUATION

My wife left her computer unused for many months. The battery ran
out and it was left 100% dead for a good while.

When charging it back up and trying to log in, the machine will not accept my wife's machine password (she had written it down previously). We've tried over 50 iterations. We tried all passwords and all permutations of any Apple passwords past and present. No dice.

So far, no method of resetting the password has been successful.

The machine seemingly can't connect to the internet to reset the password via Apple ID even though I have verified it is connected to Wifi. I tried multiple networks to rule out faulty internet. It rejects incorrect passwords, so I know it actually connects when the Wifi credentials are entered correctly. At this point, her Apple ID is the only credential I can independently verify is accurate.

My wife inadvertently activated FileVault and can't remember if/where she stored the Recovery Key. Big &quot;uh-oh.&quot;

Because FileVault is active, I cannot access the macOS Utilities (⌘+R held while booting) to run the 'resetpassword' command in the Terminal. It only boots to the Recovery OS which isn't helpful.

I also am locked out of single-user startup (⌘+S held while booting) which is disabled when FileVault is active. I was hoping to run some command-line codes to reset the password or create and admin account. Can't do any of that with FileVault enabled.

The 'Macintosh HD' Startup Disk is encrypted in the Recovery Assistant. It asks for an unlock password, but I have no idea what to enter. Any attempt has been unsuccessful.


Need some insight!
Have you tried this method?  From this source:

Use Recovery Mode to reset your password
You'll need to boot your Mac into Recovery Mode in order to access the
password reset tool. I've found the easiest way to do that is to turn
off your Mac.
With your Mac turned off, press and hold the Command and R keys on
your keyboard, then press the power button. Hold in Command+R until
you see a progress bar show up below the Apple logo. You can also get
into Recovery Mode by restarting your Mac and trying to time the
keyboard combo of Command+R, but in my experience, starting with your
Mac turned off is the most reliable method.
With your Mac now in Recovery Mode, click on Utilities in the menu bar
followed by Terminal. A new window will show up, waiting for you to
enter a command. Type &quot;resetpassword&quot; as one word, without the quotes,
and press Return.
Close the Terminal window, where you will then find the Reset Password
tool. A list of all user accounts on your Mac will be on display. To
reset the password for your account, you'll need to set a new password
for all users. Make sure you write down the new password for anyone
who shares your Mac.