Try this:

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.OleDb;


internal static string GetSingleValueFromFile(string emailAddress) {
    string returnValue = string.Empty;
    string sql = string.Empty;
    

   sql = "SELECT PASSWORD FROM " + "[" + "yourFileName.csv" + "] WHERE EMAIL = '" + emailAddress + "'";


    string textFileConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + "C:\temp" + ";Extended Properties='text;HDR=Yes'";
    try {
        using (System.Data.OleDb.OleDbConnection Conn = new System.Data.OleDb.OleDbConnection(textFileConnectionString)) {
            using (System.Data.OleDb.OleDbCommand Command = new System.Data.OleDb.OleDbCommand(sql.ToString(), Conn)) {
                Command.CommandType = System.Data.CommandType.Text;
                Conn.Open();
                using (System.Data.OleDb.OleDbDataReader dataReader = Command.ExecuteReader()) {
                    if (dataReader.HasRows == true) {
                        while (dataReader.Read()) {
                            if (!dataReader.IsDBNull(0)) {
                                returnValue = dataReader.GetValue(0).ToString();
                            }
                            else {
                                returnValue = string.Empty;
                            }
                        }
                    }
                }
            }
        }
    }
    catch (Exception ex) {
        

        throw;
    }
    return returnValue;
}