Usually new preferences are created when you restart your Mac or an app. However, depending on what you deleted, your Mac may not restart and you'll have to reinstall the system using your system install disc. Or do you have a backup from which you could retrieve the preferences?
This site contains user submitted content, comments and opinions and is for informational purposes only.
Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site.