Hi sardessardes,

You could try to use the AutoCompleteExtender control.

In aspx:

<form id="form1" runat="server">
        <div>
            <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"></asp:ScriptManager>
            <asp:TextBox ID="txtContactsSearch" runat="server"></asp:TextBox>
            <ajaxToolkit:AutoCompleteExtender
                ServicePath="WebService1.asmx"
                ServiceMethod="SearchEmployees"
                TargetControlID="txtContactsSearch"
                MinimumPrefixLength="1"
                CompletionInterval="100"
                CompletionSetCount="10"
                OnClientPopulated="Employees_Populated"
                OnClientItemSelected=" OnEmployeeSelected"
                ID="AutoCompleteExtender1"
                runat="server"
                FirstRowSelected="false">
            </ajaxToolkit:AutoCompleteExtender>
        </div>
    </form>

    <script type="text/javascript">
        function Employees_Populated(sender, e) {
            var employees = sender.get_completionList().childNodes;
            for (var i = 0; i < employees.length; i++) {
                var div = document.createElement("DIV");
                div.innerHTML = "<img style = 'height:50px;width:50px' src = 'photos/"
                + employees[i]._value + ".jpg' /><br />";
                employees[i].appendChild(div);
            }
        }
        function OnEmployeeSelected(source, eventArgs) {
            var idx = source._selectIndex;
            var employees = source.get_completionList().childNodes;
            var value = employees[idx]._value;
            var text = employees[idx].firstChild.nodeValue;
            source.get_element().value = text;
        }
</script>

Code behind:

[System.Web.Script.Services.ScriptMethod()]
        [System.Web.Services.WebMethod]
        public static List<string> SearchEmployees(string prefixText, int count)
        {
            using (SqlConnection conn = new SqlConnection())
            {
                conn.ConnectionString = ConfigurationManager
                        .ConnectionStrings["NorthwindConnectionString1"].ConnectionString;
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "select EmployeeId, FirstName, LastName from" +
                     " Employees where FirstName like '%'+ @SearchText + '%'";
                    cmd.Parameters.AddWithValue("@SearchText", prefixText);
                    cmd.Connection = conn;
                    conn.Open();
                    List<string> employees = new List<string>();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        while (sdr.Read())
                        {
                            employees.Add(AjaxControlToolkit.AutoCompleteExtender
                               .CreateAutoCompleteItem(string.Format("{0} {1}",
                               sdr["FirstName"], sdr["LastName"]),
                               sdr["EmployeeId"].ToString()));
                        }
                    }
                    conn.Close();
                    return employees;
                }
            }
        }

More details, please check the following links:

http://www.aspsnippets.com/Articles/Render-images-in-autocomplete-list-of-ASP.Net-AJAX-AutoCompleteExtender.aspx

https://ajaxcontroltoolkit.devexpress.com/AutoComplete/AutoComplete.aspx

Best regards,
Dillion