I've been using wordpress fine for about 2.5 years, up until Wednesday.
Since then, three of the admins have been unable to access the WP dashboard menu or option. Instead, we get diverted back to the homepage and the WP dashboard menu, which is usual present for logged in admins, simply says "Dashboard" without any of the options. If I try to force to go the admin page, then it comes back with the error of "sorry, user does not have permission", perhaps meaning the role has been deleted?

I've done a DB check and repair, and it came back with the DB was fine. I've removed the plugins and tried doing that, but no change. I've tried forcing a theme change, but that caused the screen of white death. I've also tried doing a reinstall of WP but nothing changed there.

Really at desperation point here as well as we have 1000+ posts that we can't afford to lose.