I have a 250 cc trail rover atv it won't start. At first it would start up fine with start button. Then after about a month when I pressed the start button nothing happened only a clicking sound. I jumped the starter and fired right up and after running the atv for about 45 mins I could start it with the start button like normal. Eventually it got to the point where the start button doesnt make that clicking noise and when I jump the starter it just cranks but doesnt turn over. Changed the spark plug and nothing. Help please?

 

Check the plug for spark when you crank it.
Pull the spark plug put it in the boot let it hang down on the motor and crank it over , watch the gap between the plug for a spark if it's there then the issue is fuel or compression if not I'd check fuses and coil and cdi.
BTW get a new batter put it in once you get it running and then make sure it's charging.