If you used and paid for one of the 2017 TurboTax online editions of either Plus, Deluxe, Premier or Self-Employed, then you have access to all your prior year online tax returns through October 2019. Provided that you are signing onto the online account with the exact same User ID you used to create the 2017 account.
To access your prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF) or View adjusted gross income (AGI)
You can also get free transcripts of your federal return from the IRS - http://www.irs.gov/Individuals/Get-Transcript