Major visual issue with cycles rendering

Question

Im rendering a scene using cycles which looks absolutely perfect when rendering in view port mode as you can see in the first image But when I finally render it, it looks like this I'm using 2.79 and i tried it on 2.78 with the same result. any help is appreciated.comment below if you need more information

Answer 1

I have fixed the issue,

most of the objects had suddenly had invisibility checked, uncheck these and it will appear fine