| Without knowing the bike brand, model etc, the basics would be to shut the fuel supply off. Change the oil that is diluted with fuel. Check the ignition for spark and timing. Check the float in the bowl for being stuck or leaking and the level is correct and that there is nothing holding the needle off the seat.Checking compression would also be a good idea so you have a feel for the health of the engine.
It takes three things to make an engine run fuel, air and spark. Remove any one of these and she will not run. A stuck float can dump enough raw fuel into an engine to gas foul plugs (wet plug) so there is no spark. | 
