Hi,
I wonder how to get back to the initial predefinitions after you did a Ctrl+U to save your own.
See you.
admins doesn’t like crossposting so I will just tell what to do…
if on XP, do something like this:
funny is, this post is in this forum as well 
Blender General
or just locate/search for the file .Bblend on your computersystem and delete it, then fire up Blender again, Voilá [!] [!] 
good luck!
i just thought i’d mention it’s .B.blend
It’s in C:\Windows on win95/98/ME
it’s in docs and settings\etc\etc\etc as above in XP
it’s in /home/ in linux