You can purchase a download of TurboTax for 2017 at the following link.
http://turbotax.intuit.com/personal-taxes/past-years-products.jsp
You might get a better price from a reputable online seller that still has TurboTax for 2017 in stock.
Tax returns for past years cannot be e-filed. You will have to print your 2017 tax return, sign it, and file it by mail.