Unplug the refrigerator from the wall and open up the freezer.
Take out the screws that hold the ice maker in place, and unplug it from the back of the fridge to expose the water inlet valve.
Aim a hairdryer at the water inlet valve to melt the ice inside. Plug the ice maker back in and test it.
Follow the water supply tube from the back of the fridge to the saddle valve. Tighten the saddle valve all the way, and then open it back up to clear any mineral deposits.
Inspect the tubing at the back of the fridge. Replace the inlet valve if there is damage to it. Unscrew the panel that covers the inlet valve and unplug the wiring from the valve. Put the new valve in place and reconnect it.