Can you get into your 2020 online account? Do you see the 2020 .tax or pdf file?
You have to log into the same account. You need to start entering some basic personal info for 2021 for the side menu to open up. Just continue a little ways into 2021.
Access prior year online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...
Then to open the .tax2020 file in the Desktop program, the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW). Enter some basic information, then go to the state tab and download the state program. Then try to open your existing return, go to FILE - OPEN
