How to troubleshoot issues with the Orphaned users

This will lists the orphaned users:

 EXEC sp_change_users_login 'Report'

If you already have a login id and password for this user, fix it by doing:

 EXEC sp_change_users_login 'Auto_Fix', 'user'

If you want to create a new login id and password for this user, fix it by doing:

 EXEC sp_change_users_login 'Auto_Fix', 'user', 'login', 'password'

CREATE LOGIN <login_name>   
WITH PASSWORD = '<use_a_strong_password_here>',  
SID = <SID>;