If you travel to Oceania then you will find an Australian Embassy or Consulate in almost every country. Most do not process the Australian visa in the country so you will need to contact the Embassy and ask which Australian Embassy manages the visa process in your area. Many of these countries are very small and will only be able to provide consular assistance.
Below you will find a number of Australian offices in the region and you should email them or call them first. If you have lost your passport then you need to ensure that you have all the documents included a police report docket number.