I had this happen to me today,. I came in this morning and all but one note were missing, and like everyone else have been having difficulties trying to contact Evernote. I then tried opening Evernote in chrome in an incognito window and that did the trick. It might be a case of clearing your browser cache/cookies, but will be backing my notes up now!
I came to work this morning and all my critical notes have been deleted. I've been going in a loop for about 30 minutes now and there is no forward way to send an email for help.