Ask @patrice to unban you via cheetahbot after you clean out the bad posts' content. You likely did what several people did (including me), which was log in to a false login page with your credentials. The login page looked exactly like Steemit's but was generated by clicking on a malicious link in a post.

From now on, you can monitor all of your account's activity by going to steemd.com/@yourusername. I did this to monitor what the ID thief was doing and respond to admins ahead of the curve.