You mean the tab called "Actions"? I have one on my Outlook but pretty sure it's not your missing tab. I don't like Outlook and am afraid to mess around too much with it, but there should be a feature that allows you to either contact or chat with someone from MSN who might give you the secret to restoring your Actions tab. My guess is that somehow you turned it off or rendered it invisible, and it should be "easy" to get it back.