Below is information for how to access prior year returns, which will also apply to 2016 and 2015 if they were filed with TurboTax.
https://ttlc.intuit.com/replies/5574744
Note that if you are not able to access your prior year returns, you can
apply to obtain a free online copy of your prior return transcripts or order a paper copy from the IRS. See more information below:
