All my Music is gone in itunes!

I did nothing to make it disappear. Im freaking out i have over 1000 songs. How do i get my songs back? when i click on music on itunes, It brings me to a window that says Music: Songs and music videos you add to itunes appear in music in your itunes library. to play a song, just double click it. No Music what so ever!!!! I have tried restarting my computer, but nothing!! Please Help!!