Hello and welcome to JustAnswer services. This is Anas and I will be assisting you with your issue today. I am sorry for the troubles you are facing.
I know that can be frustrating. Hopefully, we can get this resolved quickly. As I understand you are facing an issue with your Mac.
You'll need to boot your Mac into Recovery Mode in order to access the password ***** tool.
Please turn off the Mac first. Then 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.
With your Mac now in Recovery Mode(macOS Utilities screen), click on Utilities in the menu bar followed by Terminal. It is at the very top of the screen not on the list in the middle. A new window will show up, waiting for you to enter a command. Type resetpassword as one word and press Return.
You will then see the Reset Password ***** now. Follow the prompts selecting the user account you need to change the password ***** Or select your account and set password ***** Restart from Apple menu and see if you can login with the new password.
Please follow the link given below for detailed video instructions to unlock your Mac. Watch the video from 1:45 minutes onwards.
Please let me know if the issue is fixed, if not, we will find another way.
Please let me know if you need further assistance.
Keep safe always.