Cant get Special characters to work


I am not able to pull from the API character names with special characters inside, like Cyrillic or whatever these are Ðýßåíæõðìø, for all the other characters even the Taiwan or Chinese ones I can make it work, if anyone could give me some ideas on how can I change my code to make that also work I would appreciate it!
Thank you!

$namea = mb_strtolower($fields['name'], mb_detect_encoding( $fields['name'] ));
$name = urlencode(preg_replace('/\s+/', '', $namea));

this code should help with these characters in php