If you used TurboTax to complete and file a 2018 tax return, then download the PDF, print the Form 1040, sign and date the Form 1040 for FAFSA.
To access your current or prior year tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF)
If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created. TurboTax does not store online any returns completed using the desktop editions.