My iTunes library has completely disappeared during a download of some music from the store

This morning, during a download of some music from the iTunes store, iTunes appeared to crash, as the downloads all paused and the spinning wheel appeared. Itunes then shut itself. After reopening it, all of my music, apps, vids, etc (everything), had disappeared, and iTunes was basically blank as if I had just opened it for the very first time on my computer, with iTunes match, Home Sharing, etc all signed out.

I know this has happened for other people but having looked through the discussions they all seem to be under different cirumstances. I'm running a mid 2012 2.9 Ghz macbook pro with 8GB memory, on OS X 10.8.5, with itunes version 11.1.1 which I updated to, around a week ago, when prompted to by the app store.

I've located all the music files on my hard drive in the iTunes media folder and everything appears to be there, just no longer showing in the iTunes app. I know that if I sign into iTunes match that I'll be able to access my library through that online, but I'd like to access the music on my hard drive so I don't need an internet connection to listen, so is there any way of just re-directing iTunes to the media folder or do I need to just import everything from that folder manually?