Heat the frozen section of a pipe with a hair dryer, a heating pad, a space heater, a heat lamp or hot towels. Heat tape wrapped around the pipes also melts the ice quickly. Never use a blow torch, open flames, kerosene heaters or charcoal stoves to thaw the pipes.
Before thawing the pipes, turn on the faucet attached to the pipe. This allows the water to flow once it starts thawing to prevent pressure buildup. The flowing water can also help with the thawing process. Shutting off the water supply to the pipe or to the whole house can prevent water damage. When a pipe cracks due to the ice, water starts pouring from the crack as soon as the ice melts.
When applying heat, start on the end of the frozen section closest to the faucet. This allows the water to move through the pipe and into the faucet without as much pressure building up. Move down the pipe toward the colder end as the ice melts. Keep any heating implements away from flammable items, especially space heaters that get extremely hot.
Keep a bucket and towels handy as you thaw the pipes in case you discover cracks. If you discover cracks, call a plumber to replace the pipes before turning on the water supply.