Sometimes the pipe may be out of sight or reach in which case some very unique measures have to be taken. We all can figure that it takes heat to help that a pipe that you can have access to. Using a hair drier, heating pads etc do work, but only if you can get to the pipe. So we have to assume your not getting any water at all.
The tip I have to offer may take some time doing, but it works. Find the faucet closest to the water source where it may be frozen. Attach some kind of hose over the faucet (the type that has the soft rubber adapter on the end) or how ever you may be able to do so. Put a funnel on the open end and raise above the faucet level just a few feet. Open the cold water faucet.
With the hose attached and funnel in place take some boiled hot water and slowly pour the water into the funnel until the water either melts the ice or slowly backs up. If it backs up, you know you've reached the blockage and the heated water begins to thaw the ice even if the water cools down it still warmer than the ice.
Eventually as it starts to thaw, the pressure from the other side of the blockage will be sufficient enough to push through the remaining softened ice and your home free.
Depending on how much ice is in the pipe is going to determine how long it will take. Other than the methods for a visible pipe, this is one that works and sometimes doesn't. Another really great method is to use your own if you have one, or borrow one from a neighbor, or just go out an buy it. It's a steamer. The portable type that is used for getting wrinkles out of curtains or removing stains etc. Affix the steamer hose to the faucet and let it just steam away until it thaws the ice.
You may want to shut off the main water supply that comes in from the outside of the house. This is the one underground that has a metal cover that is removed for the meter reader. You don't want the water gushing out once the pipe is thawed, unless your going to sit with it till it does.