I forgot my MacBook Air password and there is no question mark to say forgot password.

For 2FA account .

• Close all applications and shut down the Mac , press command , R and power key simultaneously , release only power key and keep on holding command and R key until apple logo appears , the bar starts loading let it be completed .

• Select the language as English , go to utilities on top menu bar > Utilities > Terminal execute a command resetpassword and click on enter key .

• A window will appear if you can’t login to your computer because you forgot your password , you can reset it now .
• Enter new password ……
• Verify password ….
• Hint … 
• Enter the credentials and click on next .

• It will show your account password has been reset , you may restart and sign in using new password , click on exit to recovery utilities , go to apple logo and restart the Mac .
• The admin password was reset through recovery mode , when Mac system preferences was opened , click on apple id icon an error shows update Apple ID settings , some account services will not be available until you sign in again , click on continue it will prompt to enter Apple ID password , after a short while it prompted to enter old admin password ( if you remember it ) enter it the pop up goes away , again in system preferences - the keychain box is unchecked , click on it setting up finally checked every thing is normal .
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• If you don't remember the old admin password and enter the latest changed password it will show error and prompt to reset icloud keychain , cancel or use another device to reset , if you reset iCloud Keychain all iCloud passwords will be erased .
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• So , followed this method .
• See the article https://support.apple.com/en-in/HT203783
• If iCloud Keychain is corrupted in Mac .
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• ( a ) Use an iPhone and sign in with same Apple ID and password in your Mac .
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• ( b ) In iPhone go to settings , iCloud open keychain and click on advanced two options will be shown reset code and reset iCloud Keychain , click on reset iCloud Keychain .
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• ( c ) A verification code will appear on your mobile number through sms and it will prompt to generate a code , think of code and fill up in the field so keychain will be set up in iPhone , write down this code .
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• ( d ) Come to Mac in system preferences > click on iCloud the box of keychain is unchecked , so tap the keychain box , it will show waiting for approval click on option button , enter the passcode that is generated in iPhone , click on confirm .
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• ( e ) Again in iPhone a pop up will appear showing approve or deny for name of Mac to approve for keychain , click on allow .
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• ( f ) In Mac click on option button enter trusted number a sms will appear having a verification code , enter it hence the trusted number will be saved and visible and finally keychain is set in Mac ( turned as on ) .
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• In user library > keychains it is verified that password is changed .

Only if you have set a passcode reminder, can you see that question mark on the login screen.

1. Steps of resetting password via login screen (by security questions, Apple ID, etc.)https://support.apple.com/en-us/HT202860
2. Steps of removing password using macOS Recovery. https://support.apple.com/en-us/HT212190

if either way can’t solve your problem, then you might need to erase your startup disk and reinstall macOS, which deletes all of your data as well as passcode.