Here is the code
File dir = new File(Environment.getExternalStorageDirectory(), "/Audio/MI2.MID");
Uri Note=Uri.fromFile(dir);
RingtoneManager.getDefaultType(Note);
RingtoneManager.isDefault(Note);
RingtoneManager.setActualDefaultRingtoneUri(getApplicationContext(), RingtoneManager.TYPE_RINGTONE, Note);
But It is setting my phone's default ringtone..