Vauxhall Omega car won't start after cambelt change

have you done a compression test as it has an interferance engine,they usually suffer from valve damage when the belt brakes.
does it sound normal when turning over

as mr suzuki has sai its most likely going to be bent valves which will need replaceing and lapping in which means removing the head and replacing the valves also the head will need skimming so its nice and flat when replaced