not able to view images in media when logged in

I hope someone can help.

This website has sudden stopped showing majority of it's images.
Some images do show but only if the user is viewing a post.

When i log into the backend and click on media, no images are showing as thumbnails and when i click on the image nothing shows there either. All i see is a grey 'document' icon in place of where the image should be.

To add to this i have now noticed that when i make a changes they do not save. Wordpress tells me the change has been saved but when i look again it has not changed.

Has anyone any ideas to what could be causing this issue?

So far i have:
-updated everything - no change
-changed themes to 2014 and tested - no change
-disabled plugins and tested - no change

I am running out of ideas. Any help would be much appreciated.

Many thanks