2002 Chevy Trailblazer Won't Start

Disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil, distributor pick-up coil, ignition control module, cam and crank sensors-

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time/broken or jumped timing belt/chain