You should be able to access a copy of your 2016 return filed through TurboTax using the instructions below. NOTE: If you filed using TurboTax Free Edition, you'll be required to purchase (at a minimum) the 2018 PLUS feature. Access to prior years' returns is not a feature included in TurboTax Free Edition. Do you recall if you e-filed the return, or did you mail it? Your return "may" have been rejected by the IRS for some reason, and you never fixed and re-submitted the return.
"How do I access my prior years' returns?"
https://ttlc.intuit.com/replies/5574744
If the IRS says they never received the return, you'll still need to prepare and mail your 2016 return now. To do that, you'll need to purchase TurboTax 2016 software to be downloaded to your computer. You'll complete the return, print and sign it, and mail it in. I recommend mailing by certified mail so that you have proof that the IRS received your return. I'm linking the TurboTax webpage where you can purchase the downloadable software.
https://turbotax.intuit.com/personal-taxes/past-years-products/2016/
***If you paid for TurboTax 2016 when you filed, you won't be required to purchase the product again. If that's the case, please contact TurboTax Customer Support during business hours for assistance. The info below will instruct you on contacting Support.
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
*** 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.***
