Engines need two things to run, fire and fuel. You know you have a good battery, so now see if you have "spark". Check to see if the power is reaching the spark plugs. If you do, then you know it has nothing to do with the battery, wires or plugs.

Next check fuel delivery. Is fuel getting to the engine? On an old fashioned carb it is an easy check, but with these new cars you need to go primitive. You have to crank it a bit while giving it throttle and then use your nose. If you smell gas, then you are getting fuel.

If you have both fuel and fire, then there are two other problems that could be working against you. The first is a timing issue. If you timing belt/chain is gone, the engine will not start. This is usually pretty obvious as when you crank the car, it is rough and not like a normal start.

If while you are cranking the X and the engine is turning in a normal fashion. And you have confirmed that you have both fuel and flame, then the problem is most likely digital in nature. Some chip or sensor acting up. If this is the case it will most likely not be a home fix, if nothing else, because tracking the chip or sensor down requires the right computer program.

These are just a few ideas in order of how I would investigate the problem.

stasiman