A block is a measure used to protect a community from bad behavior. Blocks can apply to a user account, an IP address, or a range of IP addresses. If you have been blocked, there are a few steps you can take to try and get your block removed.
How do I appeal a local block?
If you have been blocked on one community, and you do not know why, or you disagree with the reason, stay calm. The last thing you want to do is become disrespectful or argumentative, because that might just make the situation worse. If you want to appeal your block, you should message the administrator who blocked you or follow the instructions in the block message.
The name of the admin who blocked you will appear on the block notice that you see when you try to edit a page. You may be able to contact them by leaving a message on your Message Wall or user talk page, depending on which one that community uses. You may still be able to post to your page, depending on whether the administrator has allowed that, and messages you leave on your own page will be seen by the administrators. Your page can be found by following the "My talk" or "Message Wall" link in the drop down menu from your avatar, at the bottom left of any page.
If the administrator has not allowed you to edit on your wall or talk page, you can try leaving them a message on Community Central. They will have a Message Wall on Community Central where you can contact them, and they will receive a notification letting them know that you have left them a message. If your block was made by an automated filter, check Special:ListAdmins on the wiki and contact any of the active ones.
Sometimes, though, administrators will reject the block appeal, for a variety of reasons. If this is the case, then you should wait out the block (if it is not indefinite) or join another of the many thousands of communities available.
How do I appeal a global block?
If you are accidentally caught in a global block targeted towards your username or IP address, please. In order to effectively locate the block and look into the matter, you must include all of the information in the box you see while you're blocked (which can be seen when you try to edit a page), especially the block ID.
If you are caught in a content block that is blocking addition or modification of content on a page, please use this form and give the most information possible.