457"B" deferred compensation plan- we early withdrew funds that were roth contributions. The 1099-R form provided from TIAA box 7 is 2B. TT not accepting B and cant file

The combination of codes 2 and B in box 7 of your Form 1099-R is correct.  TurboTax should accept it.  If you haven't already, I suggest you go back through the entry of your Form 1099-R and make sure that all entries are correct.  If it still won't accept the 2B combination try deleting the form and re-entering.  Finally, if it still won't accept it, circle back and post at what point you are seeing an error and what exactly are you seeing, and let us know if you're using TurboTax Desktop or Online.

When TurboTax asks if the distribution was from a Roth IRA, make sure that you answer No.  A Roth 457(b) is not a Roth IRA.  If you mistakenly answer Yes, TurboTax will later flag it as an error.