My wife has a Macbook running 10.5. She was searching her computer for large files to delete, and (entering her password first) deleted Appkit, a 61 MB file, and WebCore. I've been ignoring WebCore for the time being, but AppKit is obviously a crucial part of the system. Terminal is no longer working on her computer, along with most other software, though Finder seems to be. The AppKit file now resides in the root directory. I believe that it needs to be in the /System/Library/Frameworks/AppKit.framework/Versions/C directory but I do not have the permission to move the file there, and the lock icon in folder window is doing nothing when I click it. The data on her hard drive is incompletely backed-up, and I was wondering if there was anything that could be done to salvage it (and the operating system) at this point.