Im already reading data from excel linq based on column name and row number, I want to add sheetname in my existing code

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C#

selenium

My Excel Utils Code
   public class ExcelUtils
 {
        xl.Application xlApp = null;
        xl.Workbooks workbooks = null;
        xl.Workbook workbook = null;
        Hashtable sheets;
        public XSSFSheet sheet = null;
        public string xlFilePath;

        public ExcelUtils(string xlFilePath)
        {
            this.xlFilePath = xlFilePath;

        }
        public class Datacollection
        {

            public int rowNumber { get; set; }
            public String colName { get; set; }
            public string colValue { get; set; }
        }
        private static DataTable ExcelToDataTable(String fileName)
        {

            //open file and returns as Stream
            FileStream stream = File.Open(fileName, FileMode.Open, FileAccess.Read);
            //Createopenxmlreader via ExcelReaderFactory
            IExcelDataReader excelReader = ExcelReaderFactory.CreateOpenXmlReader(stream); //.xlsx

            excelReader.IsFirstRowAsColumnNames = true;
            //Return as DataSet
            DataSet result = excelReader.AsDataSet();
            //Get all the Tables
            DataTableCollection table = result.Tables;
            //Store it in DataTable
            DataTable resultTable = table["Sheet1"];

            //return
            return resultTable;
        }
        //static List<Datacollection> dataCol = new List<Datacollection>();
        static List<Datacollection> dataCol;
 public static void PopulateInCollection(string fileName)
        {
            dataCol = new List<Datacollection>();
            DataTable table = ExcelToDataTable(fileName);

            //Iterate through the rows and columns of the Table
            for (int row = 1; row <= table.Rows.Count; row++)
            {
                for (int col = 0; col < table.Columns.Count; col++)
                 {
                    Datacollection dtTable = new Datacollection()
                    {
                        rowNumber = row,
                        colName = table.Columns[col].ColumnName,
                        colValue = table.Rows[row - 1][col].ToString()
                    };
                    //Add all the details for each row
                    dataCol.Add(dtTable);
                }
            }
            fileName = "";
        }
        public static String ReadData(int rowNumber, string columnName)
        {
            try
            {
               // DataFormatter formatter = new DataFormatter();
                //Retriving Data using LINQ to reduce much of iterations
                string data = (from colData in dataCol
                               where colData.colName == columnName && colData.rowNumber == rowNumber
                               select colData.colValue).SingleOrDefault();

                //var datas = dataCol.Where(x => x.colName == columnName && x.rowNumber == rowNumber).SingleOrDefault().colValue;
                return data.ToString();
            }
            catch (Exception e) { throw e; }
            {
                return null;
            }
        }

/////////and calling this Method in Test Case
public class Login
{ 
[Test]
        //[TestCaseSource(typeof(BaseTest), "BrowserRunWith")]
        public void ValidCredntialTest_01()
        {
               var login = new PageObject.Login(driver);
                login.ClickLogin();
                TestContext.Out.WriteLine("+++++Clarity click has happened++++++++");
                 var LoginPagecredential = login.ClickLogin();
                
           //Here Url Stored in App.config and Calling 
  ExcelUtils.PopulateInCollection(@ConfigurationManager.AppSettings["ExcelDocPath"].ToString() + @ConfigurationManager.AppSettings["LoginFile"].ToString());
                  
// here im Caliing Username and Pass word from Excel
                LoginPagecredential.LoginToApplication(ExcelUtils.ReadData(1, "UserName"), 
                 ExcelUtils.ReadData(1, "Password"));
                test.Log(Status.Info, "Login With valid Credentials");
                TestContext.Out.WriteLine("*****Fetching UserName and Password from Excel and clicked to Login*******");
                //Caliing Inventory Page For Testing
                driver.Close();
                test.Log(Status.Info, "ValidCredntialTest_01 TestCase Passed");
            }
            catch(Exception ex)
            {
                throw ex;
            }
          }
}

What I have tried:

I tried But Getting Error and i could not find Solution
im My Code Sheet1--- is Static so here i want ,, Pass Sheet name And Fetch vaues