If you are a US citizen you are visa exempt. Perhaps that is why you are confused. Since you already had a TRV assume you are not from a visa exempt country.
You are allowed to travel to the U.S on your expired TRV. You can't travel to a 3rd country from the U.S. If you have lost or misplaced your passport with the expired TRV, then you will have to apply for a fresh TRV.
In short, as long as you have a expired TRV sticker on your passport, you can return to Canada on the expired TRV, provided your status is valid. Since you have a valid study permit, you will be allowed to enter Canada with the expired TRV.
Do not travel to any other country, otherwise this exemption is not valid.