I manually edited
/etc/passwd for non-root user - yeah, I know this is bad.
Unfortunately I saw this (SSH failing authentication after manual edit of /etc/passwd and /etc/shadow) very late.
I already recovered
/etc/passwd to previous state, but something strange is happening on the server, for example:
doesn't create home directory for this user, and doesn't ask about it password, authorization for old user is not working. I hope someone already encountered such a problem. P.S. I use Debian