You can use Time Machine to restore it if you have been using TM to do backups.
Just go back in Time to a date when you had the original fonts installed and replace the following:
/Applications/Font Book
~user/Library/Fonts ***
~user/Library/FontCollections ***
*** This is providing that you installed your own fonts and had them placed in these locations (Check your Font Book Preferences). You should never install new fonts (non apple) in the /Library/Fonts folder.