Immediately remove the phone from water and pat it dry with a towel. Remove the sin card and the battery and then use a vacuum cleaner to dry its insides. Drop the phone in a bowl of rice for at least two hours and let the rice absorb the remaining moisture. Once you feel that it is sufficiently dry, replace the Sim card and battery and then power it on. If it still does not work after all this, take it to the phone company for replacement.