language character problem. how to change utf8?

hi.

i want to use this script in turkish.
when i translate the template i cant see turkish characters ? ö ü ..etc.. it shows ?? or nothing instead of turkish alphabet.
i could not find the true file to edit.

<meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\">\n";

i want to change this to <meta http-equiv=\"content-type\" content=\"text/html; charset=ISO-8859-9\">\n";

but it doesnt effect. what is the true file to edit?
could you help me