found it in snippet 'php stuff' on sourceforge.net. The author is Antik.
function unconvert_htmlspecialchars($string) {
if (strlen($string) < 1) {
return '';
} else {
$string=str_replace(' ',' ',$string);
$string=str_replace('"','"',$string);
$string=str_replace('&','&',$string);
$string=str_replace('>','>',$string);
$string=str_replace('<','<',$string);
return $string;
}
}