I too have lost a note - which I'd been working on for the whole afternoon, so I'm very frustrated! Working on an iPad, and went into the notebook section to move it from Inbox to another notebook - and it just went! Not in trash, nowhere else in my notebooks. I find this really alarming as my reason for subscribing to Evernote rests on its stability and reliability (although I can't afford the top notch subscription).
I can't find quite the same problem listed by other users, and I don't seem to be able to get into the web version of my account either from my iPad or my mac.