If you know that your taxes were filed via TurboTax Online last year, but on a different account, you can attempt to recover the 2017 account by:
https://ttlc.intuit.com/replies/3302318
Once the account is recovered, you will find the AGI here:
Where to find your 2017 AGI in TurboTax Online/Mobile
- Make sure you’re signed in to your TurboTax account.
- Select Tax Home from the left menu.
- Scroll down to Your tax returns & documents and select 2017.
- Select View adjusted gross Income (AGI).
