页面清空。

foreach (UIElement item in this.LayoutRoot.Children)
            {
                if (item is TextBox)
                {
                    (item as TextBox).Text = string.Empty;
                }
                if (item is ComboBox)
                {
                    (item as ComboBox).SelectedValue = null;
                }
                if (item is CheckBox)
                {
                    (item as CheckBox).IsChecked = false;
                }
            }