Why won't truck atart

What year is the truck?. Check fuel filter,check fuel pressure. If fuel is ok, check crank shaft sensor, check spark at spark plugs. If spark is ok and on time, meaning spark is on when TDC, If timing and firing order is ok, do a compression test. If older truck with external ignition coil, check voltage at coil after ignition switch is turned from start to run, it should still be hot 12.4vdc, if not, replace ignition switch under steering column.

I'd start by checking that fuel is getting to cylinders, from there check spark