Has anyone experience w/ WordPress (MultiSite) hidden users (possibly hacked)?

I would first of all change the password for phpMyAdmin because I think they moust be getting though the DB next thing is if that doesn’t work , but the bullet and do a clean install but backup all the post and maybe the comments if you want ot.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)