3 Major things?
spark , fuel, compression
will it crank?
do you hear the fuel pump cycle?
getting spark?
need more info please
mud
In determining whether or not a motor is capable of running, you have the three things that mudpie just outlined.
Electricity is always first, since the repari of an electrical component can easily outweigh the worth.
Take a spark plug out, lay it on the engine cover or some way to ground the threaded end. Then, spin the motor over, watching to see if you have spark at that plug. IF not, then the reason it's not starting may be due to electricals. Check all your fuses. If you have to, because of not finding a good ground for your plug, you can buy a special tester at your local auto parts store for this procedure.
Next, fuel. You can turn the engine over several times, then pull a plug to see if it's wet with gas. If not, then you could have a fuel pump or problem with the fuel leaving the tank to the engine. When you first put your lanyard on, you should be able to hear the fuel pump run for a minimum of 2 seconds, pumping up the system.
Air? Make sure your engine is getting the air it needs for combustion. No obstructions.
Any codes in the info center?.......:cheers: