If your Facebook account is hacked, the hacker may change your password, email, and other personal information, locking you out. They might use your account to post inappropriate content, send spam or phishing messages to your friends, or steal sensitive data like photos and messages. Your personal information could be exploited for identity theft, and your contacts might be targeted with malicious links. It’s important to act quickly by using Facebook's account recovery tools to regain control, change your password, and enable two-factor authentication. Notify your friends about the hack to prevent them from falling victim to scams.