iTunes has vanished!

Hi,

I was downloading the latest update to iTunes when my pc crashed halfway through the download. After rebooting, I found my iTunes wasn't there anymore.

I'd like to restore iTunes with all of my music and videos intact, not just the iTunes store purchases. Will downloading iTunes all over again bring everything back, or will that only bring back the music/videos I downloaded from the store? How do I make sure all of my music and videos are intact?

I still have some files related to iTunes on my computer, such as 'iTunes media', but no iTunes itself.