Hi nabilabolo,

Check this example. Now please take its reference and correct your code.

For this exampe i have used ClosedXML to export to excel. Refer below link for more details.

Export DataTable (DataSet) to Excel file in ASP.Net MVC

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

Namespaces

using System.Data;
using System.IO;
using System.Linq;
using ClosedXML.Excel;

Controller

public class HomeController : Controller
{
    // GET: Home
    public ActionResult Index()
    {
        string customerId = "ALFKI";
        List<OrderModel> orders = new List<OrderModel>();
        CustomerModel customer = new CustomerModel();
        using (NorthwindEntities db = new NorthwindEntities())
        {
            orders = (from o in db.Orders
                        join c in db.Customers
                        on o.CustomerID equals c.CustomerID
                        where o.CustomerID == customerId
                        select new OrderModel
                        {
                            OrderID = o.OrderID,
                            OrderDate = o.OrderDate,
                            Freight = o.Freight
                        }).ToList();


            customer = db.Customers.Where(x => x.CustomerID == customerId)
                            .Select(c => new CustomerModel
                            {
                                CustomerID = c.CustomerID,
                                Name = c.ContactName,
                                Address = c.Address
                            }).FirstOrDefault();
        }

        DataTable dt = ToDataTable(orders);

        using (XLWorkbook wb = new XLWorkbook())
        {
            var ws = wb.Worksheets.Add("OrderDetail");
            var aCode = 65;
            var wsReport1 = ws.Range(string.Format("A{0}:{1}{0}", 1, Char.ConvertFromUtf32(aCode + dt.Columns.Count - 1)));
            wsReport1.Merge();
            wsReport1.Style.Border.OutsideBorder = XLBorderStyleValues.None;
            wsReport1.Value = string.Format("ID : {0}", customer.CustomerID);

            var wsReport2 = ws.Range(string.Format("A{0}:{1}{0}", 2, Char.ConvertFromUtf32(aCode + dt.Columns.Count - 1)));
            wsReport2.Merge();
            wsReport2.Style.Border.OutsideBorder = XLBorderStyleValues.None;
            wsReport2.Value = string.Format("Name : {0}", customer.Name);

            var wsReport3 = ws.Range(string.Format("A{0}:{1}{0}", 3, Char.ConvertFromUtf32(aCode + dt.Columns.Count - 1)));
            wsReport3.Merge();
            wsReport3.Style.Border.OutsideBorder = XLBorderStyleValues.None;
            wsReport3.Value = string.Format("Address : {0}", customer.Address);

            ws.Row(3).InsertRowsBelow(1);

            ws.Row(4).Style.Border.OutsideBorder = XLBorderStyleValues.None;
            ws.Row(4).Style.Border.RightBorder = XLBorderStyleValues.None;
            ws.Row(4).Style.Border.LeftBorder = XLBorderStyleValues.None;

            int rowIndex = 5;
            int columnIndex = 0;
            foreach (DataColumn column in dt.Columns)
            {
                ws.Cell(string.Format("{0}{1}", Char.ConvertFromUtf32(aCode + columnIndex), rowIndex)).Value = column.ColumnName;
                ws.Cell(string.Format("{0}{1}", Char.ConvertFromUtf32(aCode + columnIndex), rowIndex)).Style.Border.OutsideBorder = XLBorderStyleValues.None;
                ws.Cell(string.Format("{0}{1}", Char.ConvertFromUtf32(aCode + columnIndex), rowIndex)).Style.Font.Bold = true;
                columnIndex++;
            }
            rowIndex++;
            foreach (DataRow row in dt.Rows)
            {
                int valueCount = 0;
                foreach (object rowValue in row.ItemArray)
                {
                    ws.Cell(string.Format("{0}{1}", Char.ConvertFromUtf32(aCode + valueCount), rowIndex)).Value = rowValue;
                    ws.Cell(string.Format("{0}{1}", Char.ConvertFromUtf32(aCode + valueCount), rowIndex)).Style.Border.OutsideBorder = XLBorderStyleValues.None;
                    valueCount++;
                }
                rowIndex++;
            }
            Response.Clear();
            Response.Buffer = true;
            Response.Charset = "";
            Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            Response.AddHeader("content-disposition", "attachment;filename=CustomerOrders.xlsx");
            using (MemoryStream MyMemoryStream = new MemoryStream())
            {

                wb.SaveAs(MyMemoryStream);
                MyMemoryStream.WriteTo(Response.OutputStream);
                Response.Flush();
                Response.End();
            }
        }

        return View();
    }

    public DataTable ToDataTable<T>(List<T> items)
    {
        DataTable dataTable = new DataTable(typeof(T).Name);

        //Get all the properties
        PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
        foreach (PropertyInfo prop in Props)
        {
            //Setting column names as Property names
            dataTable.Columns.Add(prop.Name);
        }
        foreach (T item in items)
        {
            var values = new object[Props.Length];
            for (int i = 0; i < Props.Length; i++)
            {
                //inserting property values to datatable rows
                values[i] = Props[i].GetValue(item, null);
            }
            dataTable.Rows.Add(values);
        }
        //put a breakpoint here and check datatable
        return dataTable;
    }
}

Screenshot