I recently ran into same problem as the original poster. With the excerpt, etc disappearing on one account, but making a new account brought it back.
The someone pointed out the obvious to me. If this happen to you first check that these “missing” options are checked under screen options inside the invididual posts. It’s at the top. It’s sort of hidden, and I had totally forgotten it was there. Somehow excerpts, tags, post time, etc had all been unchecked. Maybe a cookie problem? Either way once they are rechecked they start working again. No need to create a new account.
