What do I do if it’s not letting me file my state taxes when I completed everything ?

Go through the REVIEW tab and see if it tells you why you can't efile.   This time of year it's usually due to a state form not being ready yet for efiling.    What state is it?

You can check state forms availability for your state here:

State Forms Availability Table:
https://ttlc.intuit.com/community/forms/help/state-forms-availability-table-for-turbotax-individual-...

Or did you already efile the Federal return separately by itself?   If you have already efiled the Federal return by itself separately, it won't let you efile the state return until the Federal return has been accepted.  The IRS will not open up to start processing until February 12, 2021, except for a few returns they pull early for testing purposes.