GridView disappears on select edit and update - asp.net

Question

I have a GridView with a sql Source, which is bound to a searchbox. The problem is that on Postback the GridView disappears. I have tried to DataBind the GridView in the PageLoad event but the problem is that the Data is coming from the searchbox so On Postback it takes out the value of the Searchbox and searches for it.
<%# Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Archiv.aspx.cs" Inherits="AutoVerwaltungASP.Archiv" %>
<%# Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<asp:TextBox id="searchbox" Value="Search..." runat="server" ForeColor="Gray" onblur="if(this.value=='')this.value=this.defaultValue;" onfocus="if(this.value==this.defaultValue)this.value='';" />
<asp:Button Text="Suchen" runat="server" ID="btnSearch" OnClick="btnSearch_Click" Height="34px" Width="90px" Font-Size="Small"/>
<asp:Button Text="Reset" runat="server" ID="btnClear" OnClick="btnClear_Click" Height="34px" Width="90px" Font-Size="Small"/>
<cc1:AutoCompleteExtender ServiceMethod="markensuchen"
MinimumPrefixLength="2"
CompletionInterval="100" EnableCaching="false" CompletionSetCount="10"
TargetControlID="searchbox"
ID="AutoCompleteExtender1" runat="server" FirstRowSelected = "false">
</cc1:AutoCompleteExtender>
<asp:GridView ID="GridView1" runat="server" AllowSorting="True" AutoGenerateColumns="False" BackColor="White" BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4" DataSourceID="SqlDataSourceAutos" ForeColor="Black" GridLines="Vertical" DataKeyNames="m_id" >
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:CommandField ShowDeleteButton="True" ShowEditButton="True" ShowSelectButton="True" />
<asp:BoundField DataField="m_id" HeaderText="m_id" SortExpression="m_id" InsertVisible="False" ReadOnly="True" />
<asp:BoundField DataField="m_name" HeaderText="m_name" SortExpression="m_name" />
<asp:BoundField DataField="m_h_id" HeaderText="m_h_id" SortExpression="m_h_id" />
</Columns>
<FooterStyle BackColor="#CCCC99" />
<HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
<RowStyle BackColor="#F7F7DE" />
<SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#FBFBF2" />
<SortedAscendingHeaderStyle BackColor="#848384" />
<SortedDescendingCellStyle BackColor="#EAEAD3" />
<SortedDescendingHeaderStyle BackColor="#575357" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSourceAutos" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT [m_id], [m_name], [m_h_id] FROM [marke]" FilterExpression="m_name LIKE '%{0}%'" ConflictDetection="CompareAllValues" DeleteCommand="DELETE FROM [marke] WHERE [m_id] = #original_m_id AND [m_name] = #original_m_name AND [m_h_id] = #original_m_h_id" InsertCommand="INSERT INTO [marke] ([m_name], [m_h_id]) VALUES (#m_name, #m_h_id)" OldValuesParameterFormatString="original_{0}" UpdateCommand="UPDATE [marke] SET [m_name] = #m_name, [m_h_id] = #m_h_id WHERE [m_id] = #original_m_id AND [m_name] = #original_m_name AND [m_h_id] = #original_m_h_id" >
<DeleteParameters>
<asp:Parameter Name="original_m_id" Type="Int32" />
<asp:Parameter Name="original_m_name" Type="String" />
<asp:Parameter Name="original_m_h_id" Type="Int32" />
</DeleteParameters>
<FilterParameters>
<asp:ControlParameter Name="m_name" ControlID="searchbox" PropertyName="Text" />
</FilterParameters>
<InsertParameters>
<asp:Parameter Name="m_name" Type="String" />
<asp:Parameter Name="m_h_id" Type="Int32" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="m_name" Type="String" />
<asp:Parameter Name="m_h_id" Type="Int32" />
<asp:Parameter Name="original_m_id" Type="Int32" />
<asp:Parameter Name="original_m_name" Type="String" />
<asp:Parameter Name="original_m_h_id" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
public partial class Archiv : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
GridView1.DataBind();
}
}
[System.Web.Script.Services.ScriptMethod()]
[System.Web.Services.WebMethod]
public static List<string> markensuchen(string prefixText, int count)
{
using (SqlConnection conn = new SqlConnection())
{
conn.ConnectionString = ConfigurationManager
.ConnectionStrings["ConnectionString"].ConnectionString;
using (SqlCommand cmd = new SqlCommand())
{
cmd.CommandText = "select m_name from marke where " +
"m_name like #searchbox + '%'";
cmd.Parameters.AddWithValue("#searchbox", prefixText);
cmd.Connection = conn;
conn.Open();
List<string> marken = new List<string>();
using (SqlDataReader sdr = cmd.ExecuteReader())
{
while (sdr.Read())
{
marken.Add(sdr["m_name"].ToString());
}
}
conn.Close();
return marken;
}
}
}
private string SearchString = "";
public string HighlightText(string InputTxt)
{
string Search_Str = searchbox.Text;
// Setup the regular expression and add the Or operator.
Regex RegExp = new Regex(Search_Str.Replace(" ", "|").Trim(), RegexOptions.IgnoreCase);
// Highlight keywords by calling the
//delegate each time a keyword is found.
return RegExp.Replace(InputTxt, new MatchEvaluator(ReplaceKeyWords));
}
public string ReplaceKeyWords(Match m)
{
return ("<span class=highlight>" + m.Value + "</span>");
}
protected void btnSearch_Click(object sender, EventArgs e)
{
SearchString = searchbox.Text;
}
protected void btnClear_Click(object sender, EventArgs e)
{
searchbox.Text = "";
SearchString = "";
GridView1.DataBind();
}
}
}