@א-ש if your database is damaged, then immediate retrieval won't be possible. Do you at least have a backup of the database ? From the comment below around accepting the loss of posts and users, it doesn't seem to be the case.
What I always do is take a copy of the CSS and keep it up to date in a text file outside of NodeBB.
I tried the other emailer (nodebb-plugin-emailer-ssl-smtp) and that works... weird, as I had the local emailer working before, when I had it on my freebsd machine (now centos).
