[UserDetail]
UserID=xxxxxxx
PassWord=xxxxxxxx

[Connection]
contact=C:UsersinfinityDesktopaadinathfilesALL EVENT FILE FORMATTRADING MASTER FILEISE CLEINT MASTER.xls
DebitISE=C:UsersinfinityDesktopaadinathfilesALL EVENT FILE FORMATTRADING MASTER FILEISE 1.xls
DebitLKP=C:UsersinfinityDesktopaadinathfilesALL EVENT FILE FORMATTRADING MASTER FILEISE CLEINT MASTER.xls

[FilePath]
DebitISEClient=C:

[FileName]
DebitISEClient=Contact_06-07-2015.txt

private void button1_Click(object sender, EventArgs e)
        {

            string filepath = txtpayoutfile.Text;

            string message = "";
            string mobileno = "";
            string name = "";
            DataSet dsmaster = new DataSet();
            string filepathc = ini.IniReadValue("Connection", "contact");
            if (filepath == "")
            {
                MessageBox.Show("Import Contact File");

                this.Show();
            }
            if (Path.GetExtension(filepath) == ".xls")
            {
                oledbConn1 = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filepathc + ";Extended Properties="Excel 8.0;HDR=Yes;IMEX=2"");
            }
            else if (Path.GetExtension(filepath) == ".xlsx")
            {
                oledbConn1 = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepathc + ";Extended Properties='Excel 12.0;HDR=YES;IMEX=1;';");
            }

            oledbConn1.Open(); ////exception occurs here


            if (Path.GetExtension(filepath) == ".xls")
            {
                oledbConn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filepath + ";Extended Properties="Excel 8.0;HDR=Yes;IMEX=2"");
            }
            else if (Path.GetExtension(filepath) == ".xlsx")
            {
                oledbConn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties='Excel 12.0;HDR=YES;IMEX=1;';");
            }

            OleDbCommand cmdoledb = new OleDbCommand("Select * from [Sheet1$3:3000]", oledbConn);
            OleDbDataAdapter daoledb = new OleDbDataAdapter(cmdoledb);
            DataTable dt = new DataTable();
            daoledb.Fill(dt);
}