Our pipes froze what do I do!? ?

I woke up to find that the hot water would not turn on. The cold does. But no shower for me this morning. yuck! So i called my husband and he said they still wern't working. (2.5 hours later) How long until they thaw out or whatever? We've turned the cold water on and left it dripping. Will it start working again as it warms up today? I hope so!