Stop changing parts and quessing. You will probably create additional problems. Diagnose the problem then replace the part that is bad. Sounds difficult but it works, less costly and less work. You only need a little information and knowledge to do it.

Does battery/starter turn the engine over OK when you turn the key to start?
If yes do you have spark at the plugs?
If yes do fuel pumps run while attempting to start?

The answers to the above will narrow down the problem to a very few possibilities.
--
David Hunter