Whatever happens is not always for good

Some people always say that whatever happens happens for good, how can everything be good? Suppose someone has an accident and both his legs are lost in the accident due to which he will never be able to walk again, then what good did it do to him, it is not like that. How can everything be for good? Whatever is happening wrong is wrong, how can it be right, so we just start living according to the circumstances because there is no other option.