Small Engines (Lawn Mowers, etc.): engine want start, fly wheel, compression tester

Question
what could be the problem i have a 18.0hp 42in. mower eight years old model of engine 31h777 type 0228-e1.while cutting the engine let out a puff of black smoke and went dead and want start no more noise in the engine when you spin the fly wheel what could be the problem thank for your help.

Answer
Try to turn the engine over by rotating the flywheel with your hand.  Does it rotate freely?  It sounds like you broke a connecting rod.  You can verify this by removing the spark plug and doing a compression test with a compression tester.  No compression most likely means broken connecting rod