If you used the Online web version you can download the .tax2020 and pdf files again.
Sorry, if you used the Desktop installed program and can't find the .tax2020 file it is gone for good. Turbo Tax doesn't save or store the tax file even if you efiled it. The only copy is on that computer and any backups you made.
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/...
If you can't find your return and you filed, you can request a transcript from the IRS
https://www.irs.gov/individuals/get-transcript
