The program was saying that I didn't enter my agi from last year correctly, so it said to file by mail instead. i found my last years agi, so i just want to efile my taxes, and now it won't let me go back.

[DoninGA]

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state.  See screenshot

This will take you back to the 2018 online tax return.

1. From the menu on the left, select File (tap in the upper-left corner to expand the menu on mobile devices). This will put you on the [Name], just X more steps and we'll file your returns screen.
2. Go to Step 3 (if needed, revisit Steps 1 and/or 2 to activate Step 3).
3. Proceed, and make sure you've selected the option I want to e-file.
4. Continue through the screens, and soon you'll see the place to enter your 2017 AGI.
5. Keep going until you’ve re-transmitted your return.