Code:

public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Button butt;
protected System.Web.UI.WebControls.DataGrid DataGrid1;
protected int sIndex;
    
private void Page_Load(object sender, System.EventArgs e)
{
}
private void butt_Click(object sender, System.EventArgs e)
{
Binding();
}
public void Binding()
{
string veza="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\Inetpub\\wwwroot\\NekiFolder\\baza.mdb";
            
OleDbConnection conn=new OleDbConnection(veza);
string strCom;
if(IsPostBack)
{
sIndex =0;
strCom = "SELECT TOP 1 id FROM tabela1 ORDER BY id DESC" ;
OleDbCommand countCommand = new OleDbCommand(strCom, conn);
conn.Open();
OleDbDataReader countReader=countCommand.ExecuteReader();
if(!countReader.Read())
{
DataGrid1.VirtualItemCount=0;
}
else
{
DataGrid1.VirtualItemCount= countReader.GetInt32(0);
}
conn.Close();
}
strCom="SELECT TOP 20 id, a1, a2, a3, a4 FROM tabela1 WHERE id < "+(DataGrid1.VirtualItemCount-(sIndex-1) )+" ORDER BY id DESC";
OleDbCommand fCommand=new OleDbCommand(strCom, conn);
conn.Open();
OleDbDataReader fReader=fCommand.ExecuteReader();
DataGrid1.DataSource=fReader;
DataGrid1.DataBind();
conn.Close();
}

private void DataGrid1_PageIndexChanged(object source, System.Web.UI.WebControls.DataGridPageChangedEventArgs e)
{
DataGrid1.CurrentPageIndex=e.NewPageIndex;
sIndex=(DataGrid1.CurrentPageIndex*DataGrid1.PageSize);
Binding();
}