Use "add a state" to get back in your return to make corrections (before filing).
1. Sign In to TurboTax Online
2. Click "My TurboTax" menu
3. Press "Visit My Tax Timeline"
4. Under the "SOME THINGS YOU CAN DO" heading, choose "Add a state" (you're not really adding a state, this allows you to get back into your return).
5. Complete/correct as needed