The state often times will not send out the 1099-G if they already know that you did not itemize on your Federal return. If you did itemize, however, and remember how much refund you received, you can enter the information in the same area of TurboTax and select the option that states you did not receive a 1099-G to report the refund.
This FAQ has additional information to guide you: https://ttlc.intuit.com/replies/5358269