Car won't start after dying twice while driving

My very educated guess is that the engine died when it overheated. You restarted and kept on driving, then the engine overheated to the point that you damaged it. That's why it won't restart. You're likely now looking at an engine replacement which might exceed the value of the car.

Rapid clicking is a symptom of a dead battery or a bad battery cable connection. However, since you said the heater stopped working before it died I suspect you had a large, sudden, coolant loss, the engine severely overheated and either burned out the starter or locked up the engine. Coolant temperature sensors are designed to work while submerged in the coolant. When you have a major coolant loss and the sensor is not submerged in coolant the sensor is not sending a signal that the engine is overheating. The warning light will not necessarily come on and, if equipped, the temperature gauge may drop to the cold position. I actually had that happen to me once. After I parked my car and went into work one of the radiator hoses burst. I was driving home, after work, and the engine started knocking. I immediately pulled over, shut off the engine, and discovered the radiator was bone dry! The temperature warning light never came on!! The engine was knocking because the excessive heat made the oil very thin! If I hadn't immediately pulled over and shut off the engine, the engine would have been ruined!! Hope that helps! Jim