How to check that well formated excel file going to upload

<form enctype="multipart/form-data">
    <input type="file" id="excel-file" name="excel-file" />
    <input type="submit" />
</form>

protected void Page_Load(object sender, EventArgs e)
{
    if(this.IsPostback)
    {
        var yourFile = this.Request.Files["excel-file"];
    }
}

private void Excel_Inspector(string Path_to_your_selected_file)
        {
try{
            //create excel application object
            Microsoft.Office.Interop.Excel.Application Excel_App = new Microsoft.Office.Interop.Excel.Application();
            //create excel workbook object and open the excel file for inspection
            Microsoft.Office.Interop.Excel.Workbook Excel_Wbk = Excel_App.Workbooks.Open(Path_to_your_selected_file);
            //this will make excel visible (you can set it to false if you like)
            Excel_App.Visible = true;
            //this will count how many sheets your excel has
            int sheet_number = Excel_Wbk.Sheets.Count;
            //loop through all excel sheets reading how the sheets are named
            while (sheet_number >= 1)
            {
                //check if sheet name is "DATA"
                if (Excel_Wbk.Sheets[sheet_number].Name == "DATA")
                {
                    /* create string var and assign the value to it - in this case I am reading
                     * cells "A1" number format. Please note that if you have date value it will
                     * NOT say "short date" or "long date". instead it will show you the actual format.
                     * For example "yyyy/dd/M"
                     */
                    string Number_Format = Excel_App.Range["A1"].NumberFormat.ToString();
                     //do something with number format (for now - we're just displaying it)
                    MessageBox.Show(Number_Format);
                }
                sheet_number--;
            }
            /* closing and cleanup part */
            //close and don't save the file (true = save, false = don't)
            Excel_Wbk.Close(false);
            Excel_App.Workbooks.Close();
            Excel_App.Quit();
            //release objects
            System.Runtime.InteropServices.Marshal.ReleaseComObject(Excel_Wbk);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(Excel_App);
}catch (Exception ex) 
{MessageBox.Show(ex.Message); }

private bool sheetNameValidation()
        {
            ////
            string FileName = Path.GetFileName(FileUpload.PostedFile.FileName);
            string Extension = Path.GetExtension(FileUpload.PostedFile.FileName);
            string FolderPath = ConfigurationManager.AppSettings["FolderPath"];
            string FilePath = Server.MapPath(FolderPath + FileName);
            ////
            //string ExcelConnectionString = Convert.ToString(Session["ExcelConnectionPath"]);
            string ExcelConnectionString = FileExtension(FileName, FilePath);

            string myExcelDataQuery = "Select top 1 * from [Data$]";
            OleDbConnection OleDbConn = new OleDbConnection(ExcelConnectionString);
            OleDbCommand OleDbCmd = new OleDbCommand(myExcelDataQuery, OleDbConn);
            OleDbConn.Open();

            DataTable dt = new DataTable();
            dt = OleDbConn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

            if (dt == null)
            {
                return false;
            }

            String[] excelSheets = new String[dt.Rows.Count];
            int i = 0;

            // Add the sheet name to the string array.
            foreach (DataRow row in dt.Rows)
            {
                excelSheets[i] = row["TABLE_NAME"].ToString();
                i++;
            }            
            OleDbConn.Close();

            if (!excelSheets.Contains("Data$"))
            {
                Master.showError = "Invalid excel document. Please select correct file.";
                return false;
            }
            else
            {
                return true;
            }
        }