Hi. I had a similar problem once with my mower. There could be several reasons. Did you checkif your spark plug slipped off. If you tilted the mower to to its side, the engine oil could have flooded the air filter on the top. Try leaving in an airy sunny place to dry off. If its a very old mower like mine....you may have to pour oil and then let it sit and then drain several times to unclog old very thick oiland then finally fill a very small amount of engine oil around the mark of your dip stick. Filter may need changing if all these dont work. Mine worked without filter change. The lawn mower is a very resilient being .....dont give up. Mine is atleast 10 years old or more , second hand so God knows what else happened in its life, add to it that know one changed its oil for years!!!!

If your having white smoke emmiting from the muffler, it is probibly the extra oil you put in the crankcase. It got in there from turning the mower over the wrong way. You are supposed to turn it over with the carberator facing up. Just let it run with it smoking. The engine is self cleaning all the oil out of the carberator. Happy mowing

Pull your spark plug out to see if it is covered in oil. Could be the reason it isn't starting now. Clean the spark plug with carb cleaner and replace. See if it starts. If it does, it may smoke a little til all the residual oil is burned up. Let us know how it goes!

Crazy is as crazy does....