Your needle and seat are bad and need to be replaced. And there is some trash in the fuel bowl. The motor is getting too hot and vapor locking cleans the air vents.
Take it to a mechanic and have him check it out. Most likely you have a problem with the fuel pump pumping way too much fuel into the carburetors, causing the engine to flood.
This is a common problem with some of the older mowers. Your best bet is to just let it restart and then activate the flood prevention gauge. If you do have an older mower this might not be an option and you'll have to take it in to get it looked at.
The carabartor might be the problem on it, it is taking in to much gas. Or there could be a leak causing it. Or you should take it in and have it checked.
