Student visa implications if you have lost your passport
Your passport is your most important proof of identity. If you lose it, report it to the police right away. The police report may serve as proof for embassy-related formalities. The next thing to do is contact your embassy or consulate. You will find the contact details on the Australian government website.
As your passport is associated with your student visa, you must advise the Department of Home Affairs of any change as soon as possible. Please see the specific information about this on the Home Affairs website.