Need to change system fonts to Default

Any bright ideas guys?

I changed the fonts to Arabic ones which I got from one of the posts on nokiafree. Now whenver I try to delete those fonts, I get the msg that file cant be deleted.

My fonts directory looks like this:

SYSTEM\FONTS\

PSILocT.ttf
SwissA.ttf
PSILocG.gdr


Please help me because this PSILocT font sucks bigtime ( I can't even see some system dialogue boxes properly).

Thanks & God bless you all!