language_buddy on "Was my site hacked?"

I noticed in a panic yesterday that my site seems to be overwritten by a standard WP theme. It all worked fine until 2 days ago, but now the custom ProPhoto theme that runs on my site isn't showing up. When I log into WP to turn on the "under construction mode" in ProPhoto, it doesn't actually turn on. I tried activating another theme in WP to see what would happen, and the same problem persists - my site is showing a standard WP theme and nothing changes. A blog post from February is what shows up on the home page. Any ideas what I should look into?

Thanks so much!!