Visiting Nepal you would be best advised to contact the Australian Embassy in Nepal for advice before you leave Australia. The Embassy will be able to assist you with guidance as the earthquakes in Nepal are always a present danger. If you are already in Nepal and need consular services then the Embassy can assist you with that. They have also advised anyone visiting Nepal to register their identity and location with the Embassy.
You can also apply for a visa if you are in Nepal however you will need to contact the Embassy as VFS is still not working properly in Nepal and using their call center in India at +91 022 67866006. Note that the visa applications are normally processed at the Australian High Commission in New Delhi. This was just an interim solution however the Embassy will know when everything is fully back to normal. So contact them first. The contact details are below with a map to the Australian Embassy in Nepal. If you do get lost then you only need to find the Thai Embassy in Nepal as it is around the corner.
Australian Embassy Nepal
Bansbari , Kathmandu
Telephone: 437 1678
Fax: 437 1533