Hi Shivam07,

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

HTML

Sheet Number: <asp:TextBox runat="server" ID="txtSheetNumber" />
<asp:Button ID="btnImport" runat="server" Text="Import" OnClick="ImportExcel" />
<hr />
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>

Namespaces

C#

using System.Data;
using System.Collections.Generic;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;

VB.Net

Imports System.Data
Imports System.Collections.Generic
Imports DocumentFormat.OpenXml.Packaging
Imports DocumentFormat.OpenXml.Spreadsheet

Code

C#

protected void ImportExcel(object sender, EventArgs e)
{
    string filePath = Server.MapPath("~/Files/Sample.xlsx");
    using (SpreadsheetDocument doc = SpreadsheetDocument.Open(filePath, false))
    {
        Sheet sheet = (Sheet)doc.WorkbookPart.Workbook.Sheets.ChildElements.GetItem(Convert.ToInt32(txtSheetNumber.Text) - 1);
        Worksheet worksheet = (doc.WorkbookPart.GetPartById(sheet.Id.Value) as WorksheetPart).Worksheet;
        IEnumerable<Row> rows = worksheet.GetFirstChild<SheetData>().Descendants<Row>();
        DataTable dt = new DataTable();
        foreach (Row row in rows)
        {
            if (row.RowIndex.Value == 1)
            {
                foreach (Cell cell in row.Descendants<Cell>())
                {
                    dt.Columns.Add(GetValue(doc, cell));
                }
            }
            else
            {
                dt.Rows.Add();
                int i = 0;
                foreach (Cell cell in row.Descendants<Cell>())
                {
                    dt.Rows[dt.Rows.Count - 1][i] = GetValue(doc, cell);
                    i++;
                }
            }
        }
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

private string GetValue(SpreadsheetDocument doc, Cell cell)
{
    string value = cell.CellValue.InnerText;
    if (cell.DataType != null && cell.DataType.Value == CellValues.SharedString)
    {
        return doc.WorkbookPart.SharedStringTablePart.SharedStringTable.ChildElements.GetItem(int.Parse(value)).InnerText;
    }
    return value;
}

VB.Net

Protected Sub ImportExcel(sender As Object, e As EventArgs)
    Dim filePath As String = Server.MapPath("~/Files/Sample.xlsx")
    Using doc As SpreadsheetDocument = SpreadsheetDocument.Open(filePath, False)
        Dim sheet As Sheet = CType(doc.WorkbookPart.Workbook.Sheets.ChildElements.GetItem(Convert.ToInt32(txtSheetNumber.Text) - 1), Sheet)
        Dim worksheet As Worksheet = TryCast(doc.WorkbookPart.GetPartById(sheet.Id.Value), WorksheetPart).Worksheet
        Dim rows As IEnumerable(Of Row) = worksheet.GetFirstChild(Of SheetData)().Descendants(Of Row)()
        Dim dt As New DataTable()
        For Each row As Row In rows
            If row.RowIndex.Value = 1 Then
                For Each cell As Cell In row.Descendants(Of Cell)()
                    dt.Columns.Add(GetValue(doc, cell))
                Next
            Else
                dt.Rows.Add()
                Dim i As Integer = 0
                For Each cell As Cell In row.Descendants(Of Cell)()
                    dt.Rows(dt.Rows.Count - 1)(i) = GetValue(doc, cell)
                    i += 1
                Next
            End If
        Next
        GridView1.DataSource = dt
        GridView1.DataBind()
    End Using
End Sub

Private Function GetValue(doc As SpreadsheetDocument, cell As Cell) As String
    Dim value As String = cell.CellValue.InnerText
    If cell.DataType IsNot Nothing AndAlso cell.DataType.Value = CellValues.SharedString Then
        Return doc.WorkbookPart.SharedStringTablePart.SharedStringTable.ChildElements.GetItem(Integer.Parse(value)).InnerText
    End If
    Return value
End Function

Screenshot