If you perform unsatisfactory work in a task, Crowdflower (The task company) can block you from doing any more tasks. We have no control over this and cannot assist you in any way if you are blocked. What you need to do is go back to the task, click "Help > File a Ticket" and plead your case to them.
You need to take the work seriously on tasks. Major companies like IBM, eBay & Microsoft are the companies that you are performing this work for and you need to be sure you take your time and not just try to get through the task as quickly as possible.
Please do not submit a helpdesk ticket on why you were banned. Again, we cannot assist you here.