If the hair dryer does not work because the frozen pipe is in the wall, hie yourself down to your local equipment rental yard and get a wallpaper steamer. Start it up and stick the hose into the wall next to one of the pipes. Repeat at the various faucets. If you are lucky, the steam will gravitate to the freeze and thaw it out. Keep the faucet turned on because once you start getting drips from it, the flow will be restored fairly rapidly.