2000 KDX 200 Won't Start

You stated you added gas, it had oil in it I hope?!! What ratio? How is the compression? Did you try to "bump" start the bike? BTW do NOT toe the bike to bump start!!!!!!!! Probably will need more info before you get some possible solutions. Check to make sure the kill switch is not stuck or shorted to ground. Check the obvious things, damaged or broken wires, loose connections, etc.

Hey mate, take the bowl off the carb and make sure the pilot jet is not clogged. This will be the most likely cause of hard starting.

Does it even splutter? And yeah, put a new plug in first, it's the easiest thing to do

All previous posts offer good suggestions. Here's some more:

If you don't know how to check for spark you should ask someone who does. Just take the plug out, still connected to the plug wire, ground the plug to the engine, turn the engine over with the kickstarter, and watch closely for a spark to jump across the gap from the center electrode to the ground tab. Darken the light with your hand or testing inside a dark place makes it easier to see.

It's possible that if your carb float was not working properly it could allow gas to continue to flow till it flooded the engine, in which case when you pulled the plug it would be wet with gas. Turn the bike upside down to drain, clean or change the plug, check for spark, if ok, gas up, go ride, and hope you ride hard enough so the faulty float bowl doesn't allow more gas to flow than you are using.

Actually, you should fix the carb if that were the case, but there's probably nothing wrong with it.

Of course, by now you've figured out what was wrong and are riding again. So how about posting what was the problem so we can all go back to sleep?