What to do if bread dough became hard in the refrigerator
I presume that you meant a fridge, rather than a freezer.

Fridges are by design pretty dry, and the best is to cover the dough with some cling film or some other impermeable barrier. (The wet cloth will dry up pretty fast.)

The dry caked surface is just dried up dough, and can be worked back into the rest. (It may need a little bit more liquids, but not much.)