Get your taxes done using TurboTax

Do you mean you did not e-file it last year at all?  If you e-filed and it was accepted you do not need to mail it.  If it has never been filed at all then you do need to print sign and mail it.

If you forgot how to access your account use the recovery tool:

  You have to access your own account and/or  print it for yourself using exactly the same account and user ID that you used when you prepared the return.

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/

https://ttlc.intuit.com/questions/1901535-forgot-your-turbotax-online-user-id-or-password

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.