Here's an idea. Do you still have 2019 installed? Try opening 2019 program and see if you can get your 2019 return to show up in it. Go to FILE - OPEN. And see if that is the right one.
In the 2019 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 .tax2019. Then close the 2019 program. Then start a new 2020 return and transfer from the 2019 file.
What happens when you try to transfer it? See if you have any other .tax2019 files on your computer. Maybe you're trying to transfer the wrong one. Do you also have the Business program? Both the Business and Personal files end in .tax2019.
See if you have a file staring with a Tilde sign ~ like "~your name.tax2019". That file is if your computer crashes or your real file gets lost or deleted or corrupt so you can restore it. Maybe you can transfer from that one.
