First check to make sure that your Montana state return was accepted by the state. If you used TurboTax Online, you can see the status of your return on the Tax Home screen of your account. You should have also received emails updating you on your return status.
If you used TurboTax Desktop:
Select File.
Select Check E-file status.
Once you know the return was accepted, go here to track your state refund. Sometimes refunds can be delayed for many reasons.