Forgot My Mac Password, and Do not have the Recovery Key

It is possible that you never created a Recovery Key, and even if you did Apple does not retain a copy of it.

Follow these instructions: If you forgot your Mac login password - Apple Support. They include instructions in the event you are unable to reset your password.

There is a way to reset your mac account password without any data loss. This may help fix your problem

1. Restart your mac and hold command+r until you see the loading bar. Then release and wait for recovery mode to open
2. go to the menu bar and click Utilities> Terminal
3. Type in resetpassword
4. A prompt should pop up, and from there you can just follow the simple instructions to reset your password
5. Restart your mac as normal and then see if it works with your new password

Note: Your iCloud keychain will still use your old password

If this was not helpful, there are some youtube videos online that can help too

Hope this helps!

If you don't know your recovery key, you can reset it in your other apple devices if you have one. Please see this article: How to generate a recovery key - Apple Support