If you print for filing the TurboTax thinks you filed and will not let you make changes to a filed return.
To get back in use the "add a state" and it will let you back in.
https://ttlc.intuit.com/community/taxes/discussion/i-completed-my-return-and-printed-it-to-mail-a-pa...
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
