2002 kx 250 not starting!! please help!!!?

hi everyone, today i went outside to ride my kx 250 the bike was perfectly fine i kicked it over and it started the first kick, i went for a little ride up to the park, as i was ridding to the park i tried punching the throttle but at some stages when i punched it it backed off sort of like it was loosing power or wasn't getting spark, anyway the bike kept going bout 20 seconds after i arrived at the park i went to do a lap but the bike felt like it was cutting out slowly slowly as i turned the bike was losing power and just cut out on me, iv never had this problem before the bike starts every time on the first kick, i tried and tried kick the bike over it just wouldn't start, i walked it home and tried to start it again and still didn't start, the bike is in good condition and never brought me problems what could it be restricting the bike from starting????? i don't know if its the spark plug i don't know what it is, i even checked the compression that seems to be fine as well, i checked the fuel and that seems to be running fine.. somebody please help me!!!