I'm stuck, what can I do?
It may well be that the birth was not registered at all, it may be that the birth might have been registered under a different spelling of the surname, so you need to look at varying spellings. It may be that a birth was actually registered under the mother's name instead of the father's because they weren't married at the time that the child was born. In the case of a marriage, the bride might have been married under a different name than the one you know, a different surname. It may well be that with a death, somehow the death just hasn't got registered, or it could be a clerical error that when the courtly returns in three months to the Registrar by the Registrar General, the entries got missed out, and so when they indexed, they weren't there to be indexed. It's best to go back to the registration office to see whether the registration might be there, and if it has been overlooked.