1. System problem: If this is a temporary failure, you can try logging in to official website again to see if the badge appears again.
2. Hide option: Some badges can be hidden or displayed. If you accidentally hide them, you can find this option in the profile page and select "Show" to redisplay the badges.
3. Account number problem: If the account number and badge are bound together, the badge will disappear when the account information changes. In this case, you can contact the game customer service for help.