See this TurboTax support FAQ for an AGI - https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
To access your current or 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 to the bottom of the screen 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
If the IRS continues to reject your tax return for the 2017 AGI, then enter a 0 (zero) for the AGI. If that is also rejected then you will have to print and mail your tax return.
See this TurboTax support FAQ for the procedure to print a tax return for mailing when using the online editions - https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online...