You cannot use TurboTax Online to file for 2019. TurboTax Online is only for the current tax year, which is now 2020. To file for 2019 you have to use the CD or download TurboTax software for 2019. You can purchase a download at the following link.
Past Years' Products
You might get a better price from a reputable online seller that still has TurboTax for 2019 in stock.
Tax returns for past years cannot be e-filed. You will have to print your 2019 tax return, sign it, and file it by mail. The IRS stopped processing mailed tax returns for several months because of the Covid-19 pandemic. They recently started to process them again, but they have limited staff and a huge backlog, so it will be quite a while before your 2019 tax return is processed.
