protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e)

    {

        if (e.Item.ItemType == ListItemType.Header || e.Item.ItemType == ListItemType.Item)

        {

            CheckBox cb = (CheckBox)Repeater1.FindControl("CheckBox2");

            CheckBox cbs = (CheckBox)Repeater1.FindControl("CheckBox1");

            if (cb.Checked)

            {

                Response.Write("123");

            }

            else

            {

                Response.Write("456");

            }

        }

    }