To access your prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
Start the 2023 online tax return by entering some personal information then click on Tax Home on the left side of the screen.
On the Tax Home webpage -
Scroll down to the section Your tax returns & documents. Click on the Year and Click on Download/print return (PDF)
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.
Or go to this IRS website for free federal tax return transcripts - https://www.irs.gov/individuals/get-transcript
For a fee of $30 you can get a complete federal tax return from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
assuming you used desktop when you open the tax file a backup file is created in the same directory as the original. it will start with a "~" if you still have the 2020 program installed you can see if it will open by double clicking on it.
if both files are corrupt, your only option, assuming you filed, is to obtain either a transcript or copy of the return from the iRS
form 4506T = transcript
for 4506 = copy of return for a fee
you can obtain a transcript of the return using the iRS online services.
https://www.irs.gov/individuals/get-transcript