Is the MIL/CEL on? If so, scan it and see what codes came up and go from there.
Personally, without any more info, I would think it's the fuel pump. Can you hear it run when you turn the key "ON"? If no, then check your inertia switch, fuses, and wiring. If it runs, then:
If nothing, then check for spark & fuel. See if the plugs are sparking (all of them), make sure the injectors are injecting (should be able to hear them click if you put a stethoscope on them), make sure you have good fuel pressure. If all checks out, then check timing, as the belt might have slipped, or has a few broken teeth on it causing it to skip.
If all passes the green light, I.E. its in time, its got spark, its got fuel, then it becomes serious, because it could be the camshaft out of whack, broken or bent valve lifters, burnt out valves, or even bent connecting rods that could cause this problem. But I would quite think it's a fuel/spark/time issue, perhaps a blown coil, or a damaged belt.
That's what I would do in this situation. Somebody may have a better idea. Good luck.