protected void Button1_Click(object sender, EventArgs e)
{
    string strPath = "d:/test.xls";
    string mystring = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source = '" + strPath + "';Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";
      //"Provider = Microsoft.Jet.OLEDB.4.0 ; Data Source = '" + strPath + "';Extended Properties=Excel 8.0";
    OleDbConnection cnnxls = new OleDbConnection(mystring);
    OleDbDataAdapter myDa = new OleDbDataAdapter("select * from [Sheet1$]", cnnxls);
    DataSet myDs = new DataSet();
    myDa.Fill(myDs);
    DataGrid1.DataSource = myDs.Tables[0];
    DataGrid1.DataBind(); 
}