.com .org and similar
Often referred to as EPP Code or Registry Key
There is no retrieval tool that will send the registrant of the domain the password. So you will have to contact the registrar.
To check the registry please follow the link to the .com WhoIs
.au such as .com.au .org.au and similar
Often referred to as Auth Code, Authorisation Code or Registry Key
Follow the link to run the .au password recovery process. Please be aware that any recovery will be sent to the registrant registered email address.
To check the registrant please follow the link to the .au WhoIs
.nz such as .co.nz and similar
Often referred to as UDAI or Unique Domain Authentication Identifier
There is no retrieval tool that will send the registrant of the domain the password. So you will have to contact the registrar.
To check the registry please follow the link to the .nz WhoIs