Knocking?

2004 Mach1 (32V) 37,000miles: I had a faint tick in my engine that the dealer "couldn't tell me what it was" now its past the warrenty and yesterday my battery died (after replacing it) and unrelated to that I believe. The ticking turned into a loud knocking and on my way home from work I lost horsepower then the car died. New battery is in it of course and everything works, but the engine wont turn or even try to, the starter almost engages but its like it is locked up. I have heard about knock sensors in these engines, and of course the knocking made me think oil, but Im unsure? And the oil is good just not sure if it is going everywhere it should be. Any idea what could cause this?