My website is stuck on my logo

This morning my website was working fine. I was struggling to get Google to find my site by adding the short code into my home page, but got it done after a while. But when I checked my website tonight, all my pages were stuck on my logo. And when I go to edit each page(in pages) all the content is still there? Its just not showing. And when I load a different theme, the content shows again?
Please help, I am not sure if I did something with the codes(which I know nothing about)