Unplug your Whirlpool and move it away from the wall so you have access to the rear access panel. This is located near the bottom of the unit.
Remove the screws on the access panel and remove the panel. This will expose the internal components of the refrigerator.
Follow the copper water line from the wall to where it connects to the rear of the refrigerator.
Unscrew the attachment securing the water line to the refrigerator with a wrench.
Check the port where the line attaches for signs of freezing. Feel along the copper line for signs of freezing as well.
Plug in your hair dryer near the fridge and use it to defrost the port where the copper line connects.
Run the hair dryer over the copper line as well until all frost and internal ice has thawed. You'll know it's defrosted when all ice melts and forms droplets of water.
Reattach the water line and replace the access panel of the refrigerator. Turn on the refrigerator.