Since TurboTax 2017 online is no longer available, you'll need to purchase the CD/Download version and complete your return using that software. Additionally, prior-year returns cannot be e-filed. You'll need to print, sign and mail your return when it's complete. I recommend mailing using Certified Mail so that you have proof the IRS has received your return.
The TurboTax FAQ linked below will instruct you on how to proceed. Please post back if you have further questions.
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
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*** 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.***
