I filed my state return, but not my federal. Now turbotax won't let me into the software so i can finish working on my federal return. What's wrong?

You can't file a state return without filing federal also.  As long as you haven't mailed your federal return, you can get back in and e-file.  To get back into your return, see below.   https://ttlc.intuit.com/replies/5561257