Not sure what you are hoping to do with an unfiled 2020 return now ----but you cannot finish preparing it using online TurboTax nor can you e-file it now. The only way to finish preparing it is to download the desktop software to a full PC or Mac, and then file by mail. It is too late to receive a refund for a 2020 return---the refund was forfeited as of the final deadline on May 17, 2024 and will not be paid. However, if you owe tax due for 2020, the late fees and interest owed have been adding up since then.
It is not certain if you can even download 2020 desktop software now---it might be too late. The 2020 software is about to be "retired." If you want to try:
You will be able to access the 2020 return you started by using the exact same account and user ID that you used when you started it. But you can no longer use online software for any further changes.
Start a 2023 return online and enter some personal information so that the menu on the left opens up and lets you access your past year returns.
Online tax preparation and e-filing for 2020 returns is now permanently closed.
Now it is too late to use online software or to e-file. If you have any changes/corrections at all to make to your 2020 return, you now have to complete it using desktop software, which you must download to a full PC or Mac (not to a mobile device).Then you need to print, sign and mail it.
If you already paid for your online software you can ask customer support for a download of the desktop software.
They are available from 5 a.m. to 5 p.m. Pacific time Mon-Fri
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
No refund for 2020 will be paid. If you owe tax due, then file and pay the amount due as shown on the Form 1040, but expect a bill later from the IRS for the penalty and interest you will owe. Only the IRS will calculate this—TurboTax will not calculate it.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.