If you don't have the main .tax file you might have one that starts with a Tilde sign ~ like "~your name.tax2020".. That file is if your computer crashes or your real file gets lost or deleted or corrupt so you can restore it.
Find your Tax file in Windows
https://ttlc.intuit.com/community/tax-data-file/help/find-your-tax-data-file-tax-file-in-windows/00/...
Here's an idea. Do you still have 2020 installed? Try opening 2020 program and see if you can get your 2020 return to show up in it. Go to FILE - OPEN. Then save it again with a name and place you can find. Go to File - Save As.
