Why it happened - have not idea
How to fix - yes
Two different methods and depends on if the computer is Intel Computer or Apple Silicon M1 / M2 / M3 computer
Reset Computer Password for the Administrator Account Password
Intel Computer
Shutdown the computer
Restart computer and immediately hold the two keyboard combo Command r
If using a Bluetooth Keyboard with Rechargeable Battery - Cable the Keyboard to computer for this unique purpose. Bluetooth Kernel may not load soon enough to execute the 2 keyboard commands
Top Tool Bar >> Utilities >> Terminal
Type resetpassword as one word and no spaces
Press Return key
Follow the prompts and remember the New Password
Apple Silicon M1 / M2 /M3 Computer
Choose Apple menu > > Shut Down
If using a Bluetooth Keyboard with Rechargeable Battery - Cable the Keyboard to computer for this unique purpose.
Do not attempt a Restart to access this feature. The computer Must be Shutdown and pause for about 10 seconds before moving forwards
Press and hold the power button on your Mac until you see “Loading startup options.”
Click Options, then click Continue.
Top Tool Bar >> Utilities >> Terminal
Type resetpassword as one word and no spaces
Press Return key
Follow the prompts and remember the New Password