If the frozen portion of pipe can be found, the safe use of a heating pad, blow dryer or portable heater can thaw the pipes. Electrical heating tapes are also available at home-improvement stores that wrap around the frozen pipes, which will not only thaw the pipes but also keep them from freezing again in the future.
Do It Yourself
Because of experience and training, professional plumbers can quickly locate frozen sections of pipe and they know how to safely heat them with an industrial strength heat gun to restore water flow. Plumbers also usually have hardware on hand, such as electrical pipe heating tapes, that they can install immediately to prevent future freezes.
The decision to call in a pro depends on whether you have access to the pipes, can locate the freeze, and are physically and technically capable of doing the job. If so, do the job yourself. Otherwise, calling a professional plumber might be the best course of action.