GetPersonFromTextFile.cs

    public partial class Form1 : Form
    {
        static readonly string _defaultPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "mytext.txt");

        readonly PersonsRepository _repository;

        public Form1()
            : this(new PersonsRepository(_defaultPath))
        {
        }

        public Form1(PersonsRepository repository)
        {
            _repository = repository; 
            InitializeComponent();
        }

        void Button1_Click(object sender, EventArgs e)
        {
            _repository.Load();
        }

        void button2_Click(object sender, EventArgs e)
        {
            var personFound = _repository.FindPerson("Antanas");
            /* Do things with the persons info */
            if (personFound != null)
                MessageBox.Show($"Persons Address is : {personFound.Address}");
            else
                MessageBox.Show("No person found");
        }
    }

    class PersonsRepository
    {
        Lazy<List<Person>> _persons;

        public IEnumerable<Person> Persons => _persons.Value;

        public PersonsRepository(string path)
            => _persons = new Lazy<List<Person>>(() => ReadAllPersons(path));

        List<Person> ReadAllPersons(string path)
        {
            var list = new List<Person>();
            using (TextFieldParser parser = new TextFieldParser(path))
            {
                parser.SetDelimiters(",");

                while (!parser.EndOfData)
                    list.Add(ParseLine(parser));
            }
            return list;
        }

        Person ParseLine(TextFieldParser parser)
        {
            string[] fields = parser.ReadFields();

            return new Person()
                    {
                        FirstName   = fields[0],
                        LastName    = fields[1],
                        Gender      = fields[2],
                        Email       = new MailAddress(fields[3]),
                        Address     = fields[4],
                        DateOfBirth = DateTime.Parse(fields[5])
                    };
        }

        public void Load()
            => Persons.Count();     // count objects to force loading into memory

        public Person FindPersonByFirstName(string firstName)
            => Persons.FirstOrDefault(p => p.FirstName == firstName);
    }

    class Person
    {
        public string       FirstName   { get; set; }
        public string       LastName    { get; set; }
        public string       Gender      { get; set; }
        public MailAddress  Email       { get; set; }
        public string       Address     { get; set; }
        public DateTime     DateOfBirth { get; set; }
    }