To retrieve the password for all domains, an email will be sent out to the contact email address on that domain.
For .au domain names registered through IPMedia, you can retrieve your domain password by entering your domain name on this form.
For .au domain names registered through another company, or if you're not sure, you can retrieve the password by entering your domain name on this form.
For all other domains, you will need to contact the domain registrar to have the password sent out. If the domain is registered through IPMedia, simply lodge a support ticket.