Need prove of employment

Your W-2's would be proof you were employed and had an earned income.  Copies of a W-2 can be obtained from your employer(s).

TurboTax does not have a copy of the W-2 or Form 1099. It would have W-2 and Form 1099 worksheets that included the tax data from the forms that were entered. The worksheets would be included in the PDF of the tax return in the tax year the return was completed.

If you cannot obtain the W-2 from your employer, then for a fee you can get a complete copy of a W-2 from the Social Security Administration - https://faq.ssa.gov/en-us/Topic/article/KA-02501

You can get a free Wage and Income transcript from the IRS - https://www.irs.gov/individuals/get-transcript

You can use Social Security Form SSA-7050-F4 to request earning information by employer - https://www.ssa.gov/forms/ssa-7050.pdf

I see your self-employed and therefore you are not likely to have a w-2.   if not, all you can present in a copy of 2019 schedule C or maybe even a complete 2019 return.  but perhaps you should discuss what you need to provide with the requestor.  We're guessing.