What version of TurboTax did you use?
If you used TurboTax Online, this FAQ may help you find your returns: https://turbotax.community.intuit.ca/community/importing-transfering/help/why-can-t-i-find-my-turbotax-online-return/00/873627
If you used TurboTax CD/Download, your tax files are only stored on your computer. We don’t keep any copies. Check your “Documents” folder for a “TurboTax” folder, as that is where the software stores its files by default. You can also use Windows search to look for “.tt20”, as this is the file extension TurboTax used for 2020 returns.