ADDENDUM:
In order to prepare the 2019 return with TurboTax, you would need to use 2019 desktop software. The 2019 return cannot be prepared in Online TurboTax, which is now only for 2020 returns.
If you need to purchase 2019 software, you can buy it directly from TurboTax as a download here:
https://turbotax.intuit.com/personal-taxes/past-years-products/
The 2019 return cannot be efiled; it has to be printed, signed, dated, and mailed. It's recommended to mail by a method that has tracking such as certified mail, priority mail, etc. If you have both Federal and state returns, the Federal return goes to the IRS and the state return to the state tax agency.
If you started a 2019 return last year in Online TurboTax and didn't finish it, we can tell you how to download the *.tax2019 data file to continue preparing the 2019 return in the desktop software. If you already paid for a 2019 product last year, then TurboTax Support should furnish you the 2019 software.
