Hi MohmdNader,

You can try below link if no result will found so you can clear the textbox value on click of no result found. If by mistake you spell wrong then you need choice to correct it.

Clear jQuery AutoComplete TextBox when no match found

If you want to clear directly if no any result match when you input any value then just modify above link code with below code.

    <script type="text/javascript">
        $(function () {
            $("#txtSearch").autocomplete({
                source: function (request, response) {
                    $.ajax({
                        url: 'CS.aspx/GetFruits',
                        data: "{ 'prefix': '" + request.term + "'}",
                        dataType: "json",
                        type: "POST",
                        contentType: "application/json; charset=utf-8",
                        success: function (data) {
                            if (data.d.length > 0) {
                                response($.map(data.d, function (item) {
                                    return {
                                        label: item.split('-')[0],
                                        val: item.split('-')[1]
                                    };
                                }))
                            } else {
                                //If no records found, set the default "No match found" item with value -1.
                                //response([{ label: 'No results found.', val: -1}]);
                                $('#txtSearch').val("");
                                $("#<%=lblFruit.ClientID %>").html("");
                            }
                        }
                    });
                },
                select: function (e, u) {
                $("#<%=lblFruit.ClientID %>").html(u.item.value);                  
                }
            });
        });
    </script>
    Enter search term:
    <input type="text" id="txtSearch" />
    <asp:Label ID="lblFruit" Text="" runat="server" />

Screenshot

Thanks Kaplesh ..

I'm have to use your Example and it work excellently.

I just add some code to cs to load data from DataBase

        [System.Web.Services.WebMethod]
        [System.Web.Script.Services.ScriptMethod()]
        public static string[] GetSections(string prefix)
        {
            List<string> Sections = new List<string>();

            using (SqlConnection conn = new SqlConnection())
            {
                conn.ConnectionString = ConfigurationManager
                        .ConnectionStrings["conn"].ConnectionString;
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "select section from sections where " +
                    "section like  @SearchText + '%'";
                    cmd.Parameters.AddWithValue("@SearchText", prefix);
                    cmd.Connection = conn;
                    StringBuilder sb = new StringBuilder();
                    conn.Open();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        while (sdr.Read())
                        {
                            Sections.Add(sdr["section"].ToString());
                        }
                    }
                    conn.Close();

                }
            }

            return Sections.Where(f => f.ToLower().IndexOf(prefix.ToLower()) != -1).ToArray();
        }

Thanks Again Mr. Kaplesh