Date has DISAPPEARED

Certainly you have not customized directly a Parent Theme? Please review the Codex about use of a proper Child Theme.

Did you change the theme recently? Some themes show the date and some don’t.

no, I am using twenty twelve.

Start with disabling your plugins. It could be, for example, Comment luv that’s causing the issue but you won’t be sure untill you check ALL plugins. You can try disabling them and then enabling them one by one.

I deactivated them all, and still didn’t see the date

I see you are using a child theme. I suppose you made a change there that’s causing this issue.

yes- and I can’t seem to figure out what is making that issue appear?