kpradmin on "Can't login to Web Page. Error 500 on Chrome."

Hello,

I am very new to Word Press so please excuse my lack of basic knowledge.
I think I am using the latest version. ( I can't check because I cant access)

I started trying to change my posts page width under Appearance/ "Editor"

Under twenty Fourteen, I think I changed max width to 100% somewhere. When I pressed "up date" I received the following message "The http://www.kprconstruction.com.au page isn’t working
http://www.kprconstruction.com.au is currently unable to handle this request.
500

I can't Log in to adjust any settings.