L.C.
You don't need to change your password like the poster below (who obviously didn't read your whole message) suggested because you said you just forgot to log out -- it's not like they hacked your account!! I would contact yahoo and see if they can recover anything. They probably can't but it's worth asking. Then, do as suggested and email everyone you know and let them know due to a BUG (yes, your in-laws bug you!!!!) you lost everything that was sent on such-n-such a date so please resend anything. If people can't remember what/if they sent anything to you then at least they will know you lost a lot and will not wonder why you never responded to something specific. I don't know of any way to protect yourself in the future, other than printing things you want to keep and get to later.