You may have to start a 2020 tax return with some basic personal info before the left side column links are available.
Click on Tax Home on the left side column.
To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF)
If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created. TurboTax does not store online any returns completed using the desktop editions.
I don't think it shows all the left menu until you actually get into the 2020 tax preparation...when you first log in, all it shows is "Tax Home" and in many, but not all accounts. "Documents"
Another reason may be that you are using a narrow screen device......where you click on the hamburger stack in the upper left to get the left menu to appear.
(Never prepare your taxes on a phone...too many things missed. But that's just a personal a opinion based on umpteen thousands of users who messed up because they didn't see everything on the horribly limited phone display)