C#

public string GetExcelConnectionString(string fileName)
{
    if (fileName.EndsWith("xls"))
    {
        return @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileName + @";Extended Properties=""Excel 8.0;IMEX=1""";
    }
    else
    {
        return @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileName + @";Extended Properties=""Excel 12.0 Xml;HDR=YES;""";
    }
}
OpenFileDialog ofd = new OpenFileDialog();
ComboBox cmbTables = new ComboBox();
ListBox lstColumns = new ListBox();
Button btnShowInGrid = new Button();
DataGridView dgv = new DataGridView();
DataTable dt = new DataTable();
private void Form1_Load(object sender, EventArgs e)
{
    lstColumns.SelectionMode = SelectionMode.MultiSimple;
    dgv.AutoGenerateColumns = false;
    btnShowInGrid.Text = "Show In Grid";
    btnShowInGrid.Click += new EventHandler(btnShowInGrid_Click);
    this.Controls.Add(dgv);
    this.Controls.Add(btnShowInGrid);
    this.Controls.Add(lstColumns);
    this.Controls.Add(cmbTables);



    lstColumns.Dock = DockStyle.Top;
    cmbTables.Dock = DockStyle.Top;
    btnShowInGrid.Dock = DockStyle.Top;
    dgv.Dock = DockStyle.Fill;

    cmbTables.SelectedIndexChanged += new EventHandler(cmbTables_SelectedIndexChanged);

    ofd.ShowDialog();

    OleDbConnection conn = new OleDbConnection(GetExcelConnectionString(ofd.FileName));
    conn.Open();
    DataTable tables = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
    conn.Close();
    cmbTables.DataSource = tables;
    cmbTables.DisplayMember = "TABLE_NAME";
    cmbTables.ValueMember = "TABLE_NAME";
}

void btnShowInGrid_Click(object sender, EventArgs e)
{
    dgv.Columns.Clear();
    foreach (object o in lstColumns.SelectedItems)
    {
        DataGridViewTextBoxColumn c = new DataGridViewTextBoxColumn();

        c.DataPropertyName = o.ToString();
        dgv.Columns.Add(c);
    }
    dgv.DataSource = dt;
}

void cmbTables_SelectedIndexChanged(object sender, EventArgs e)
{
    OleDbConnection conn = new OleDbConnection(GetExcelConnectionString(ofd.FileName));

    conn.Open();
    OleDbCommand cmd = new OleDbCommand("SELECT * FROM [" + ((DataRowView)cmbTables.SelectedItem)["TABLE_NAME"].ToString() + "]", conn);
    OleDbDataAdapter da = new OleDbDataAdapter(cmd);

    da.Fill(dt);
    conn.Close();
    lstColumns.Items.Clear();
    foreach (DataColumn clmn in dt.Columns)
    {
        lstColumns.Items.Add(clmn.ColumnName);
    }


}

System.IO.Directory.GetFiles(@"\\10.10.0.50\d$");