the site looks awful in Internet Explorer and cannot edit

I am working on my website, everything went guite well but suddenly, my theme got all messed up, yesterday. I use Internet Explorer and since last night my website menues changed appearance – all in one column, the slider has ugly purple grame and slider itself does not work, there is only one of for slides as a static slider(=no slider), no text, no icons for other 3 slides. I checked for IE updates, but did not find any. Please help, what is wrong? It is ruining my work.
(appears fine in Google Chrome