Hello
Check sound knod in first !
After put you nabaztag in test mode (put on your rabbit pressing the head button (in same time) until the rabbit is white !) and test if you are sound (press the head button 2, 3 or 4 time, i'm not remember)
If you are not sound contact support : http://help.violet.net/index.php?langue=2&type=1 or change your nabaztag in the shop where you are buy you nabaztag
(Sorry for my bad english !)