To file a return for a prior tax year
Only a 2016 return can be prepared online and e-filed.
If you need to prepare a return for 2014 or 2015 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
https://turbotax.intuit.com/personal-taxes/past-years-products/
(if you want to prepare on paper for free: )
You can download the Forms and Instructions from the IRS web site:
https://www.irs.gov/forms-pubs
Remember to prepare your state return as well—if you live in a state that has a state income tax.