The CTRL+M works just for sony vaio only . It does not work for HP or something else . At first try cleaning the entire Key board , if it does not work yet that means your key is broken . Try to use the given suggestion as an alternative . If it still does not work yet just replace it with another Enter Key . You do not have to replace the whole Key board to fix it . Suggestion by 10 year old girl studing in grade seven Computer Lover . XXXX —- It works.