There are two things you need to check, fuel and spark. To me it sounds like you are not getting fuel to the carb, but I would check spark first. Get an inline spark tester at your local auto parts store. The next time it happens insert the tester between the plug and wire and check to see if you have spark, no spark I would be replacing the coil. If you have spark remove the fuel line from the carb and put it into a glass jar. Have an assistant try starting the engine and see if you get fuel into the jar. No fuel, you have either debris in the fuel line or bad fuel pump. If you post back include units model number (behind the left rear wheel) and all engine numbers, so we have a better idea what you are dealing with.