Why is my 2020 tax return not showing up in my account? I need to print it for a refinance.

How to access prior online returns

https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/01/27010

You have to log in to the same account.   You need to start entering some basic Personal Info in 2021 for the side menu to open up. Just continue a little ways into 2021.

If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online.

You can also request a transcript from the IRS

Get Transcript | Internal Revenue Service

It's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then use this TurboTax account recovery website to get a list of user ID's for an email address. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/