Wait for the loading bar to appear on the screen while your Mac boots to Recovery. Turn off your computer and hold the power button + Command R.For such cases, there’s Apple’s Recovery Mode.
There are no password hints and you can’t call it to mind, even though you’ve already tried to enter all pet names. You forgot Mac password and can’t access any of your accounts. Hope this is just a “what-if” for you, but let’s imagine it happened.