I did my last year tax's with the same computer and turbo tax 2020. Why is none of my last years information going over

Did you use the 2020 Desktop program?  Do you have the 2021 program installed?  It shows you are posting from the Online version.

Are you on Windows?

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/00/25926

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. And see if that is the right one.

In the 2020 program do a File-Save AS and give it a easy name you can find or search for. And note where it saves it or select where to save it so you can find it again. The file will end in .tax2020. Then close the 2020 program. Then start a new 2021 return and transfer from the 2020 file.

Are you on Windows 10? That can move files to different spots like to One Drive. Or to Drop Box. Could it be under a different user on your computer?

if you used online last year you must be in the same account as you used for 2020.