If the 2017 tax return was completed with the TurboTax online editions, you have to sign onto the 2017 online account using the exact same user ID that was used to create the 2017 online account.
If the desktop CD/Download editions were used and installed on a computer, the only copy of the tax data file and any PDF's will be on the computer where the return was created. TurboTax does not store online any returns completed using the desktop editions.
To access prior year online tax returns sign onto the TurboTax website with the User ID used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF)
You can also get free transcripts of your federal return from the IRS - http://www.irs.gov/Individuals/Get-Transcript
For a fee of $50 you can get a complete federal tax return from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
Or ask your lawyer to get the return for you by contacting his lawyer.