Ultimate branding - Unclosed html tag cause hiden backend content across site

Got myself in to a litte pickle here. Was styling and making an help menu for a client. And was using the admin css tool and help tool of ultimate branding when I must have forgot to close a div or another tag and now my entire content of the back end is gone.

I say gone, it is there , because if you inspect element you can see it all there. but still all the nesting seems correct, so no really sure what happen there. After some time wasted trying to edit the html in the editor to make the dashboard visible I got nowhere. So I decided to remove the plugin via ftp ,and I got my dashboard back. Now . I could try and be a hero and edit the db entries of ultimate plugin but i rather use some guidance before trying to do this without my business partner that understands this a lot better than me.Still i would like to have some sort of walkthrough or help with this matter. Never thought that the plugin could be so dangerous, because it is the help menu .. and if we mess up something like forget to close a tag we find ourselvs in a heap of trouble . Now in an ideal world there could be a wpmudev plugin to clean wpmudev plugin entries in the database. Allowing a clean slate when stuff like this happens. now another possibility would be I may have messed up some admin css class . but still , i manage to get there from another previously open tab and delete all the admin custom css to see if that would be it. So the only posibillity i that i actually forgot to close a html tag most likely a div and now im finding myself in this pickle. What is the best way to sort this out .

Thank you .