Access to prior year's return is not a feature included with TurboTax Free Edition. You will be required to purchase, at a minimum, the PLUS package for 2016.
I believe that the info below will assist you.
https://ttlc.intuit.com/replies/5574744
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
