Coolant leaking out and car will not start

My coolant was linking from top of water pump housing unit and car start running hot. Now water goes straight out the reservoir when I fill it up. I have no ideal where it's leaking from. And car won't start. I started it once and had white smoke come from exhaust for about ten minutes and a little water. Think I have water in engine to cause the oil is milking. So why it does not crank? What can be the problem? If I try to start it it cranks for awhile trying to turn over for awhile then it'll start.