Yard Machine Not Starting?

I have a Yard Machine. I just recently replaced the blades and V-belt; though being I had the mower on its side for a bit, now the mower is not starting like it should. I found that oil got into the carb bowl as well as on the spark plug. Does anyone know what this could have done? When I did briefly get it started it smoked very badly. When I shut it off it would not start again.

By Ed K. from Riverside, CA