A Canadian passport is a valuable document that should be kept in a safe place at all times. Once it has been reported lost or stolen, it is no longer valid and is not to be used for any travel. This is to ensure that it is not used for fraudulent purposes.*
Report the loss or theft
As soon as you realize or suspect that your passport has been lost or stolen, you should immediately report the circumstances of the loss or theft:
If you need to replace a lost, stolen, damaged, destroyed or inaccessible passport, please contact Passport Canada.
* Cited from the Passport Canada website