1. Paid preparers can't use the personal version of turbotax.  It doesn't contain the necessary information for use by a paid preparer which violates the Turbotax license and IRS regulations.

2. Intuit does make 2 different professional programs that are allowed for use by paid professionals.  However, the tax data files don't transfer to the personal Turbotax program.  To prepare a 2017 return, just start using the program.  Any needed 2016 information can be entered from a copy of  your prior return when you are asked for it.

3. If the preparer did use Turbotax installed on their own computer, only they have copies of your tax return, they are not online with Turbotax.

4. If the preparer used turbotax online, you might be able to call customer service and have the user account transferred to your name and email address.  Proof of identity would be required.

5. If you can't get your prior information any other way, you can request a transcript from the IRS. https://www.irs.gov/Individuals/Get-Transcript