string strData = @"{""code"":""rest_invalid_param"",""message"":""Параметр"",""data"":{ ""status"":400,""params"":{ ""status"":""Текст""}}}";

    class Posts_status_draft
    {
        public string code { get; set; }
        public string message { get; set; }
        public List<Data> data { get; set; }
    }
    class Data
    {
        public string status { get; set; }
    }

 Posts_status_draft posts_status_draft = null;
 JavaScriptSerializer serializer = new JavaScriptSerializer();
 posts_status_draft = serializer.Deserialize<Posts_status_draft>(strData);

public List<Data> data { get; set; }

public Data data { get; set; }