I assume that you've not changed your registered email address on either AB or Gravatar recently (as that would explain your missing avatar).
Click View Your Profile.
Click Edit My Profile.
Check to see if your avatar is shown there and also, importantly, whether there's a tick in the 'currently active' box.
What your actual email is doesn't really matter. All that matters is that what you've got registered with Gravatar is the same as what you've got registered with AB. (It could be [email protected], which clearly isn't a proper email address. However, if both AB and Gravatar's severs see it as such, it should still work).