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 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