Responsive Theme Broken

I’ve been using the responsive theme for a number of months now and last night I updated the theme and it is now showing as broken. It says the stylesheet is missing. Can anyone help me solve the problem? I don’t have a background in developing so I need easy step-by-step instructions if possible.

Website is arizonaeruv.org. Since the responsive theme broke, it defaulted my website to the twenty fourteeen theme. Please Help.