[X-Newbies] ITunes restore?

[Mark Taintor]

Something happened with my iTunes library the other night. When I tried 
playing a CD I got a message saying that my iTunes library was damaged 
and was being renamed iTunes Library (Damaged).Now when I open itunes, 
none of my music is there.

What do I need to do to restore everything? I do have a backup copy on 
an external HD.

Thanks in advance for any advice you can give me.

Mark