Online TurboTax can only prepare a 2019 return at this point in time. For a 2017 return, if you want to use TurboTax, you'll need to use 2017 desktop software (CD/download). And the 2017 return cannot be efiled; it has to be printed and filed by mail. I'll also tell you another option at the end of this post if you want to prepare it manually with forms and instructions from the IRS.
Did you already start a 2017 return online a couple of years ago prior to the 2017 online shutdown, and want to finish that one without starting over? If so, you can download the *.tax2017 data file from your account and finish it in the 2017 desktop software.
If you already paid for your 2017 product previously, TurboTax Support should furnish you the software.
Otherwise, you can purchase 2017 desktop software as a download at this page and install it on your computer. Then you can download the *.tax2017 data file you started 2 years ago and finish it in the desktop software.
https://turbotax.intuit.com/personal-taxes/past-years-products/2017
Minimum system requirements for Windows version:
https://ttlc.intuit.com/questions/1901571-minimum-system-requirements-for-turbotax-windows-software
Minimum system requirements for Mac version:
https://ttlc.intuit.com/questions/1899173-minimum-system-requirements-for-turbotax-mac-software
The 2017 return cannot be efiled. It will need to be printed, signed, dated, and mailed. It's a good idea to mail by a method that has tracking, such as certified mail, priority mail, etc.
If you have both Federal and state returns, you need to mail each one separately to its respective tax agency.
If you are due a Federal refund, in "normal times" it would take about 6 weeks for the IRS to process a mailed return and deliver the refund. But these are not normal times, so expect possible delays due to the Coronavirus situation.
OR another option is to download the 2017 forms and instructions for free from the IRS website and fill them out manually.
https://www.irs.gov/forms-pubs/prior-year
