It would appear that my computer has the folder listings for kcontrol and for the local applications, but none of the files. To put it another way: In the KDE Help Center, I see a list of topics, including Application Manuals and Control Center Modules. Clicking either of those names gives me a list of topics. Clicking any of those topics reports "File or folder xxx does not exist." and "There is no documentation available for yyy." xxx may be, for example, help:/kcontrol/ebrowsing.index and yyy being /kcontrol/ebrowsing.index.
Under those two selections, every file is missing. Did I accidentally uninstall a package that I needed? What package was it?