2002 Hyundai Elantra vehicle wont start

Did you put no.1 piston on its compression stroke/TDC if not the valve timing is off. If so

Do below to determine if its fuel or spark problem

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 related problem, check the fuel pressure to rule out the fuel filter/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 packs, coil's resistances, cap and rotor /distributor pick-up coil, ignition control module, ECM, Ignitor cam and crank sensors- Note: If it doesn't apply disregard it

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