Yesterday's 100 words almost didn't happen. I wasn't too busy, disinterested or forgetful; I had a database corruption.
Scarily, despite uncovering the root cause, I seemed helpless. I removed compromised cells, entire rows, reverted everything I could think of... no change!
Just before accepting defeat I found a forum thread containing the answer. Installing WP-DBManager enabled a full database repair, which fixed whatever my overtired brain couldn't find.
Those two hours were awful, but educational. Firstly, I don't understand the Wordpress backend, which is problematic when debugging. Secondly, I have no contingency/backup plan. Failing this challenge due to technical issues seems wrong.