Why doesn't my 2019 info show up in my account when I'm entering 2020 data?

You have to use the exact same User ID and password as you did for 2019.

If you do not see your 2019 tax return data, it might be in a different TurboTax account. Go here to see how many accounts you may have, one of them should have the return you're looking for and that will be the account you'll want to use for your 2020 tax return.