What color is the spark? If it is yellow or red, that is a weak spark and a new set of plugs may make a difference. If the spark is white or blue, that is a strong spark and you have the possibility of a fuel problem. You can take a little gasoline and pour it in the carburetor then crank, if it fires, you have a fuel delivery problem. If it will not fire after a bit of cranking, your problem is with ignition.
Regards
Frank