I'll tell you below how to get back into the state return as long as it has not actually been filed (has not been efiled and has not actually been mailed.)
Have you already filed the Federal return? If so, then do not make any changes on the Federal side when you open the return back up with the steps below.
- Log in and at the Tax Home go to the section "Your Tax Returns & Documents."
- Click on that line or the word SHOW to expand that section.
- Under 2018, look for a link "Add a State" and click. (that doesn't really add one; that's just to open the return back up.)
- Once the return is open, you can go to the State Taxes section and resume working on your state return to make any corrections.
- When finished click "Done with state."
- Then go through the REVIEW tab to be sure all is still in order.
- Then go through the FILE tab to choose a filing method, etc.
- If filing by mail, it should prompt you to print the return and filing instructions.
- If efiling, be sure you go all the way to the end to the final screen and click the button "Transmit My Returns Now".