Lost I photo application

Okay so I will try to make this brief. While screwing around with the"candbar" application and changing some icons, i lost my I photo application entirely. No icon, no application. First place I looked was in trash. Not even there. So I used my application install disk and I was able to get my icon back on my dock. So now when I click on it it comes up blank with the exception of a message showing that "I have made changes to my I photo library using a newer version of I photo. Please quit and use the latest version of I photo." now what do I do?

Update: I did a software update for I photo and things are back to normal.