Do you have the .tax2020 file from last year? If you used the Online version you can download it to transfer into 2021.
I assume you are on Windows?
You need the file ending in .tax2020 on your computer. 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. The .tax and pdf files should be in your Documents in a Turbo Tax folder. Or search your whole computer and Recycle Bin for all files ending in .tax or .tax2020.
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/...
If you used the Desktop program last year. 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.
