if you just Defeated onyxia and it dosent reset then please follow these
1. do .i u all if it dosent work follow my second
2.Log out from your account and character and try to see if it is reseted if not Follow line 3
3. Then please close your wow.exe and clear your chace from data and in the folder you installed wow, then log in and it should work if not so then please make an ticket