If you have the username then you should be able to get the user using the get_user_by function, which will return the user object
https://developer.wordpress.org/reference/functions/get_user_by/
$user = get_user_by(field, value);
If you have the username then you should be able to get the user using the get_user_by function, which will return the user object
https://developer.wordpress.org/reference/functions/get_user_by/
$user = get_user_by(field, value);