ERROR the theme does not exist

I have recently updated my website to wordpress version 4.2.2. I am trying to get the website to work but in appearence it says the theme directory twentyfifteen does not exist. Ive tried deactivating the theme and plugins and reactivating them, ive uploaded the theme through the FTP (not compressed) nothing i try seems to work. Wesbite http://www.createinspiremotivate.co.uk. Could someone help me try and get the theme to work. Also when I try to add a new theme through WordPress it comes up with an error saying install failed.