for (int i = 0; i < checkedListBox1.Items.Count; i++)
            {
                if (checkedListBox1.Items[i].ToString() == "1" || checkedListBox1.Items[i].ToString() == "2")
                {
                    MessageBox.Show(checkedListBox1.Items[i].ToString());

                        checkedListBox1.SetItemChecked(i, true);

                }

            }