Folders deleted during Finder file copy/cancel

I attempted to copy an iPhoto library from a MacBook Air to my iMac over wifi, using the standard Mac OS Finder commands using home network disk sharing. The copy, which was to an external hard drive on the iMac, was taking a long time (~500MB file) and I eventually cancelled it.

I didn't discover until weeks later that numerous subfolders (containing many subfolders and files each) of the folder where I had tried to copy the library had disappeared from my external hard drive. I believe some sort of corruption occurred on the disk volume during or because of the copy that didn't succeed.

I've tried running the standard Disk Utility "verify disk" process and it didn't report any errors. Interestingly, there are files that I can no longer see in the Finder, but Final Cut Pro X can still allow me to playback the original files, as they were linked to a FCP X library I was using. So something about the hard links in the FCP library allowed me to retain access to the files. However, iPhoto libraries that reference files in those lost folders will no longer allow me to open the original photos in iPhoto or the Finder. (I have configued iPhoto to not copy the files into the iPhoto library on import). Also, the space used by the lost folders doesn't seem to have been released back as free space on the disk volume.

So my question is, are there utilities anyone would recommend that might be able to re-scan the directory structure on the external drive and find those lost folders? Has anyone else hit this problem of having a directory get messed during a simple file copy?

Thanks.

(PS The fact that it was an iPhoto library I was trying to copy shouldn't have much bearing, besides the fact that that's a package structure. It was not replacing an existing library or folder of the same name.)