Okay, so this happened to us (first time homeowners in an old, poorly insulated house on a big ass hill). Our hot water froze in our bathroom. Luckily, I was able to isolate the pipes in question and spent 8 fun-filled hours on Christmas Eve half-in my drop ceiling with my hairdryer, slowly unthawing the pipes. I also had a little space heater tucked underneath the bathroom vanity.

Have you tried this method? If you know where your pipes are, try aiming a hairdryer or a space heater at them. Otherwise, might be time to call a professional.