I have had a Honda GVC 160 lawnmower for some time now and it has been ok apart from a few sputters. i was mowing the lawn when the air intake bit blew of and then a big bang came from the exhaust and a big puff of smoke also. Eversince it will not start. can anyone help

Did you throw a rod? Check compression, and piston+rod. The bang might have been a backfire. Is the engine getting gas? Did you fill oil? Overfill?