WordPress With Goodlayers Modernize theme crash

I really need some help asap.

I was uploading some high res images to the site. Next thing a box appears at the top of the screen saying HTTP error (as I recall), and now the whole back end has stopped working

I cant access the sliders as when I go to edit a page there is nothing there…

https://www.flickr.com/photos/healthgauge/7584279832/in/photostream/

And I cant edit portfolio because it is stuck like this…

https://www.flickr.com/photos/healthgauge/7584277358/in/photostream/

It’s also showing that I’ve got no media (photos), when I actually have around 50…

https://www.flickr.com/photos/healthgauge/7584363694/in/photostream

Really need some help. What could have gone wrong and how do I go about fixing it?

I am in a massive panic. What should I do?

Please help!