A few suggestions that might help. You mention that you cannot find any W-2's? Was your dad still working for an employer in 2020? If he was retired, then there would not be any W-2's since W-2's only come from employers. If he was still working, you could ask that old employer for copies of his W-2's.
And....there are a lot of different kinds of 1099's. Many come from banks or financial institutions, from which you could seek copies. Of course....you need to determine which financial institutions to contact. Did your father work as a consultant or independent contractor for anyone who would be able to provide a copy of a 1099NEC they issued to him for 2020?
You can try getting a wage and income transcript from the IRS---that would show the income that was reported to the IRS by employers, banks, financial institutions, brokerages, etc. for a federal return. The transcript will not be as helpful for preparing a state return.
https://www.irs.gov/individuals/get-transcript You want the one called a Wage and Income transcript
Or you can pay Social Security for copies of W-2's.
To get a copy of a W-2 from Social Security https://faq.ssa.gov/en-us/Topic/article/KA-02501
Was he receiving Social Security benefits? Contact Social Security to see what you need to do in order to get a copy of his SSA1099 for 2020.
https://www.ssa.gov/agency/contact/
Try getting copies of banking records from their bank. If you have POA the bank should be helpful.
You might (most likely) need to seek local paid tax help. You will not be able to use TurboTax to prepare a 2020 tax return. A 2020 return has to be filed by mail.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
