YoVille will NEVER ask for your password, so please be wary of malicious emails and/or forum posts that request your password, including via web links.
I have been [laying this game for years and for some reason I am just now hearing about the advent calendar, it has never shown up on my screen or in my mega phone. I have missed out on so much I see.
It should be popping up with the rest of the stuff daily on the right. It's numbered every day. Not sure if it makes a difference, but are you using FB or yo.com?