I have found lots of examples how to get default ringtone. Something like that:
Uri alert = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
I've also searched a lot for your problem which I also had. At last got solution from this itself.
Use below code in the button for ringtone intent.
public void pickRingtone(View view) {
// TODO Auto-generated method.stub
Intent intent = new Intent(RingtoneManager.ACTION_RINGTONE_PICKER);
intent.putExtra(RingtoneManager.EXTRA_RINGTONE_TYPE, RingtoneManager.TYPE_RINGTONE);
intent.putExtra(RingtoneManager.EXTRA_RINGTONE_TITLE, "Select Ringtone");
// for existing ringtone
Uri urie = RingtoneManager.getActualDefaultRingtoneUri(
getApplicationContext(), RingtoneManager.TYPE_RINGTONE);
intent.putExtra(RingtoneManager.EXTRA_RINGTONE_EXISTING_URI, urie);
startActivityForResult(intent, 5);
}