If you are unsure of your residency status or if you need to file a return, you will need to contact the Canada Revenue Agency (CRA) and confirm it with them. 

If you are in Canada or the United States, you can call the CRA at 1-800-959-8281. If you are elsewhere, you can call 613-940-8495. This page has more ways to contact the CRA: Contact the Canada Revenue Agency