This FAQ has information that may help you find your files if you used TurboTax CD/Download in previous years: https://turbotax.community.intuit.ca/replies/3285180
If you have already downloaded the PDF, check the downloads folder on your computer to see if it’s there.
This FAQ has information that may help you find your returns if you used TurboTax Online: https://turbotax.community.intuit.ca/community/importing-transfering/help/why-can-t-i-find-my-turbotax-online-return/00/873627