If you need to change or finish 2021 return you need to switch to the Desktop program. You can move your Online file to the Desktop program and continue without paying for Online or needing to reenter your info.
To continue in the desktop version see this…….
https://ttlc.intuit.com/community/choosing-a-product/help/how-do-i-switch-from-turbotax-online-to-th...
After you get the program installed the first thing to do before you open your tax return .tax2021 file is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW).
You can buy prior year Download here,
TurboTax® 2021 Tax Software for Filing Past Years’ Taxes, Prior Year Tax Preparation