Weirdness with Subsite and Plugin Missing

So, when I click on "my sites", one of them only shows Visit|Dashboard – does not show the name of the site (when My Sites fills the whole page, not the drop-down list.) If you try to go to the live site, it says "Error Establishing a Database Connection". You can go to the dashboard, but it shows the name of the main site at the top, instead of the name of the subsite, like the other subsites do. AND the domain mapping plugin is not under the tools menu, but it is network activated and that show in the plugin list (of the bad site). All other sites are ok, it's just the one. And the mapping plugin is ok on the other sites. What in the world?