Sorry--TurboTax no longer supports or provides updates for 2020 software. You might be able to find some other tax software for 2020 or you can seek local paid tax help. Or.....use the paper forms and prepare them by hand to mail in.
And...just so you know...any refund for tax year 2020 has been forfeited. The IRS will not send it even if the tax form shows a refund. If you owe tax due ---it is owed with late penalties and interest.
To get the paper forms from the IRS:
https://www.irs.gov/pub/irs-prior/f1040--2020.pdf
https://www.irs.gov/pub/irs-prior/f1040s1--2020.pdf
https://www.irs.gov/pub/irs-prior/f1040s2--2020.pdf
https://www.irs.gov/pub/irs-prior/f1040s3--2020.pdf