To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state.
This will take you back to the 2020 online tax return where you can make changes before filing the tax return.
But if you already mailed in the return you cannot just make changes. You must wait for the original return to be fully processed and you have the original refund in hand. Only then should you start the amendment process.
And if you have NOT yet filed a 2019 return--
The current online program can only be used for a 2020 return--no other year. And if you did not file a 2019 return you will have trouble e-filing 2020. When it asks for your 2019 AGI try using zero. If zero does not work then you have to print, sign and mail 2020.
Online preparation and e-filing for 2017, 2018 and 2019 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2017, 2018, or 2019 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.
Remember to prepare your state return as well—if you live in a state that has a state income tax.
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.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile device.
If you are getting a refund, there is not a penalty for filing past the deadline. If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.