To access your 2016 return. Please see the link below for more details.
(If you’re just looking for last year’s AGI, get more information here.)
First, make sure you’re in the same TurboTax account as previous years. Then, if you haven’t already, you’ll need to upgrade (if you're in Free Edition) and pay for TurboTax before getting access to your filed return.
https://ttlc.intuit.com/questions/3404575-how-do-i-access-my-prior-year-2016-return