I believe female spadefoots can croak, but the do not call like the males. But how do you know the frog does not have a throat pouch? It may just have never used it that you have seen. It is hard to tell if they have one or not just by looking at the deflated chin.
The most likely cause of the silent toad is a respitory infection. Does she seem to have a runny nose, wheezy breathing, or does she breath with a slightly open mouth?
Another cause could be some other type of bacterial or fungal infection that is affecting the animal's throat.
Double check your temps, humidity and water quality. Consider taking the frog to a vet.