If TurboTax thinks you were finished with the state return (but you haven't actually filed it), here's how to open the return back up:
Log in and at the Tax Home, click on "Add a State." That doesn't really add another one; it opens the return.
Once the return is opened back up, then in the left menu column click on the State Taxes tab to go through the state return interview.
After you finish the state return, go to the REVIEW tab and run the error check prior to filing.
It's also a good idea to print and review the return prior to filing.
NOTE: If you have already filed the Federal return, do not make any changes on the Federal side.