If your checked baggage has been missing for more than 21 days, you should replace its contents, and the suitcase.
Proof of Financial Loss
Ask for an itemized receipt for each item that you replace (if possible), and keep your receipts. If receipts are not available, keep detailed notes of your purchases (date, description, and amount).
Liability Limits
The airline is liable for your expenses caused by loss of your baggage up to a certain amount:
CAD$2,300 (approx.) on itineraries within Canada and international itineries, including to the US; and
US$3,800 on domestic itineraries within the US.
If your baggage is lost, the airline must also refund the baggage fee.
You can claim more than these amounts if you can prove that the loss was a result of willful misconduct of the airline and/or its agents.