If you started your 2020 taxes on desktop 2019 TurboTax, check your file manager for a copy of the 2019 return in case you did not overwrite it. TurboTax ahs copies of the 2019 return if you used Online TurboTax but does not save the desktop software returns.
You can get a free transcript from IRS Get Transcript or purchase a full copy of your federal return from that site.
