If you used the Windows Desktop program you need the file ending in .taxyyyy to open in it. The tax files (and PDF files) should be in your Documents then in a Turbo Tax subfolder. If you can't find them do a search for all files ending in .tax or .tax2021 or .tax2020, etc. And check the Recycle Bin. For Windows 10 check the One Drive. Did you make any backups? Like DropBox.
If you don't have the main .tax file you might have one that starts with a Tilde sign ~ like "~your name.tax2021". That file is if your computer crashes or your real file gets lost or deleted or corrupt so you can restore it.
Find your Tax file in Windows
https://ttlc.intuit.com/community/tax-data-file/help/find-your-tax-data-file-tax-file-in-windows/00/...
Try this......start the 2021 program. Then go up to File-Open and see if it finds your file.
If you can't find the .tax2021 file, you will have to recreate the original return with the wrong info. Then when it matches each line that you really filed you have to tell Turbo Tax you will mail it so it thinks it was filed. Then you can amend it.
