use ajax
As like
its helps you
<asp:TextBox ID="txtAccountName" runat="server" AutoPostBack="True" OnTextChanged="txtAccountName_TextChanged"
TabIndex="13" Text='<%# Eval("Name") %>' Width="150px"></asp:TextBox>
<ajaxToolkit:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" CompletionSetCount="2"
MinimumPrefixLength="1" ServiceMethod="GetLedgername" ServicePath="~/UserControls/Autolist.asmx"
TargetControlID="txtAccountName">
</ajaxToolkit:AutoCompleteExtender>