seem to have been hacked

My site seems to have been hacked, and wonder what I can do to protect the site. I googled around, but there’s too much information, and a lot of it seems old. Since there is a pretty new update, I figured I would ask.

What seems to have happened, is that someone got in and put some giant amount of code at the beginning of two of my posts such that those specific post pages did not show up in IE. They worked completely fine in Firefox and Chrome, and since I mostly use FF I didn’t notice it right away, but they were still recent posts when I did notice it.

Any thoughts?