My car died while i was driving. Jump start wouldn't work. I replaced the alternator and the battery. it cranks, but will not start. i don't know where to begin. what could it be? what do i do? what next?

 

You have to determine if it is not getting fuel or not getting spark. You can do a fuel pressure check to see if it is getting fuel. You can also spray some starter fluid or gas into the throttle body and see if it runs for a few seconds. If it does then you probably need at least a fuel pump.