On the login screen there is a 'Forgot your password' link.
Please use this to reset your password.
You will then receive an email with a link in to reset your password.
If you see 'Login name not recognized/does not exist' then check that you don't have a space in your login name.
You can remove any spaces or other characters and try again.
If this is not successful please post an issue to firstname.lastname@example.org