How did stored emails disappear in my InBox?

My emails that were saved in my Inbox were no longer there - what happened? On top of it, Yahoo does not have a recover deleted items feature like other carriers do meaning that nothing can be salvaged. Is there a reason for my saved emails disappearing without my input?|||Do you have an angry, controlling or obsessive ex-partner/partner? Could they have deleted it? Did you leave your account open on a public computer? Emails don't just disappear? Maybe if they were eons old and your account memory was full?