We have built in limits on the site that will prevent users from posting multiple times in a short time frame. It's a necessary evil that helps us to prevent most spam and spamming posts. Just make sure you leave a bit of time between posts, and that you push the "submit" button only once!
I've been blocked. Or I'm banned
Or, if alerted to being banned, you have been banned for being too abusive on the site. To submit a dispute to request this restriction be reviewed please see this article for more information and instructions.