Unable to login and am not able to reset password

Hi I reinstalled my Macbook Pro and as a result for some reason I am not able to login to the main dashboard as it says it does not recognise either the username or password

Every time I try to reset my password it says to check my email but it never sends out an email allowing me to reset the password

How am I able to resolve this so I can log in to the main dashboard?

Many thanks