How does someone remove inbox messages in your facebook?

A friend of mine who's on my facebook friends list was having a conversation with me back and forth email messages through facebook...I realized 3 days later that somehow all the messages that were sent to me in my inbox had disappeared. Anyone know how she was able to do that? She does not have my password, so she couldnt have logged into my account.|||no, they dont go away by themselves. if one person deletes one of their messages, then whoever they were talking to's message is deleted as well|||did she deactivate her facebook account! That happens if she does. Otherwise there is NO WAY she could have done that, unless she DOES know you password without you knowing, or u deleted them and forgot.|||You musta checked all messages and musta deleted em all accidentally! It just does not dissapear anywhere.! .. try checking ur sent messages folder!|||im not 100% sure but i think they go away after a little bit