If your passport has been lost or stolen, you must follow the instructions listed below:

Go to the International Student Office to get a certificate of the loss,

Report to the local police station about your case and ask for a report of the loss
Bring the report and certificate to the Chengdu Public Security Bureau and apply for a written confirmation of the loss,
       Apply for a new passport with the written confirmation at your embassy.
Go back to the International Student Office with your new passport and apply for a new student visa. Please note that you must go back to the police station to renew your housing registration as well.