My iPhoto library is gone

My iPhoto library is gone, and I don't know where.

My system was slow, so I ran the Disc Utility and it told me the disc needed repair. I took it to an Apple Store genius bar.

The "genius" told me the disc was dying, slowly. He got me to buy a portable hard drive. Then he sent me to sit in a theatre seat and told me to copy my important data files onto it.

I copied my documents, seemingly without difficulty. I tried to copy my iPhoto library. But for some reason the most recent 10 rolls of digital "film" did not copy.

Moreover, for some reason the entire iPhoto library is now missing from my original hard drive.

The "genius" wasn't too concerned. He spent 5-10 minutes looking for my iPhoto library, and shrugged. It's a consequence of an aging disc, he said, sending me on my way.

Now I'm at home trying to find my iPhoto library on my still-functioning computer. When I try to open iPhoto, it says, "Your photo library was not found. Do you want to find your iPhoto library folder?"

Yes I do. But where could it be? The "genius" looked in the obvious places. I keep searching under User, Photos, Libraries, things like that.

Any ideas? I could really use some help here.