First make sure the freezer is cold enough for the icemaker to cycle (14 degrees or below) and there is 120v getting to the i/m plug. If it's below about 14 degrees there are a number of things that can cause no operation, but the quickest fix is to replace the icemaker. (Part #4317943). The cause might be a failed mold heater, thermal link, motor, thermostat, etc. The complete i/m is about the same price now as the Whirlpool module, so I'd recommend just replacing the i/m.