Help!

When I started iTunes today it told me that it needed a library to open. Thinking this a bit odd, I nevertheless clicked on my library to open it.

However it opened my library as it was before I moved it across to a different drive (http://drownedinsound.com/articles/3383875). This means it has about 1,500 fewer songs, all my old playcounts and playlists and, most importantly it can't find ANY of the tracks (ie. the little exclamation mark pops up).

I have no idea at all why it's done this, nor how to fix it. Please help!
I have no idea