Clearing Apertures general presets would not bring them back to life.
Which "general presets" did you clear?
- The "com.apple.Aperture.plist" file in "~/Library/Preferences"
- or the general presets in ~/Library/Application Support/Aperture ?
If you have not tried both, try the other one, see the trouble shooting basics: : http://support.apple.com/kb/HT3805
You should be able to copy the settings from your own computer, by launching Aperture from a second account. If the above does not work, create a second user account (System Preferences - User & Groups) and see, if Aperture shows the Black and White settings again. If not, then you will have to reinstall Aperture, because something is wrong with your Installation.