1998 Plymouth Grand Voyager intermittant starting problems.

1998 Plymouth Grand Voyager starting problems. Van has intermittant starting problems. Occasionally, I will try to start the car and when I turn the key there is no sound at all as if the battery is disconnected. The radio, AC fan, lights all seemed to work. I will let it sit overnight and when I go out to start it the next day, it starts up just fine, repeatedly and will work for days. Then, for no apparent reason it won't start again. Current starter is 3 years old.