You access your 2019 return using exactly the same account and user ID that were used when you prepared it.  If you forget how to find it use the recovery tool:

Many people have multiple TT accounts and forget how to access them.  Log out of the account you are in now.

Account recovery

https://myturbotax.intuit.com/account-recovery/

Online tax preparation and e-filing for 2019 returns is now permanently closed.  You had until midnight on Thursday, October 15, 2020 to finish and attempt to e-file; if your e-file was rejected you had until October 31, 2020 to make corrections and re-file. 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 2019 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.

https://ttlc.intuit.com/questions/2559403-how-do-i-finish-a-prior-year-return-that-i-started-in-turb...

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 Monday-Friday.

https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number

If you are getting a refund, there is no penalty for filing late.  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.

You have to sign onto your 2019 online account using the exact same User ID you used to create the online account.

Close all TurboTax windows on your web browser (including this one).  Copy and paste the account recovery website link onto a new web browser window and run the tool.

Use this TurboTax account recovery website to get a list of all the User ID's for an email address.  Run the tool against any email addresses you may have used - https://myturbotax.intuit.com/account-recovery

If none of the user ID's received will access your 2019 account, then use the option shown in blue on the account recovery website, "Try something else"

If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created.  TurboTax does not store online any returns completed using the desktop editions.

To access your current or prior year tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on the Year and Click on Download/print return (PDF)

A 2019 tax return can only be printed and mailed, it cannot be e-filed.

Print, sign, date and mail the tax return to the IRS.  Include with the mailed return any forms W-2 and 1099 which have taxes withheld.  Go to this IRS website for mailing addresses - https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment

There are no penalties for filing a tax return after the due date if filing for a tax refund or there are no taxes owed.