Restoring Excel Fkeys settings to original values?
 

I lost the settings of my F-key shortcuts in Excel 2007 - For example, now my:
F8 is "save this worksheet." - Used to be "anchor this cell to make a
selection."
F2 is load "Word 2007." - Used to be "edit this cell."
How did it happen? - I have no idea.
Would anybody have a way to restore their settings to their original values?

Thanks

Lautaro