Sometimes, the connection between Facebook and Jetpack might get disconnected. Not to worry, the following steps should get you up and running again quickly.
- Log into your site. Go to your dashboard -> Settings -> Sharing and click the X next to the link to the Facebook profile or page you wish to disconnect.
- Reload the page and confirm the link now says Create new Facebook connection, but don’t click that link yet.
- Log into your Facebook account. Then go to your Facebook Account Settings > Apps page by clicking this App Settings link.
- Remove the WordPress.com app by clicking the X in its row. (If there is no WordPress.com row, don’t worry, just skip this step). If you see a popup asking for confirmation, click the “Remove” button.
- Log back into your site. Go to your dashboard -> Settings -> Sharing and follow these steps to reconnect.
More info here: