using System;

using System.Collections.Generic;

using System.Linq; 

​

class Person

{

    public int ID { get; set; }

    public string Name { get; set; }

    public char Gender { get; set; }

​

    public override string ToString() => "{GetType()}  {ID}  {Name}  {Gender}";

}

​

class Patient : Person { } 

class Doctor : Person { }

​

static class FinderObject

{

    // what you want to do can be done using Linq on a list with FirstOrDefault

    // so there is no real use to create the method yourself if you could instead

    // leverage linq

    public static T Find<T>(List<T> data, string Name)

        where T : Person 

        => data.FirstOrDefault(p => p.Name == Name);

}

​

public static class Program

{

    static void Main(string[] args)

    {

        var docList = Enumerable.Range(1, 10)

            .Select(n => new Doctor() { ID = n, Name = "Name{n}", Gender = 'D' })

            .ToList();

​

        var patientList = Enumerable.Range(100, 110)

            .Select(n => new Patient() { ID = n, Name = "Name{n}", Gender = 'D' })

            .ToList(); 

​

        // finds a doctor by that name

        Doctor d = FinderObject.Find(docList, "Name3");

​

        // patient does not exist

        Patient x = FinderObject.Find(patientList, "Name99");

​

        Console.WriteLine("Doc: {d}");

        Console.WriteLine($"Pat: {(x != null ? x.ToString() : "No such patient")}");

        Console.ReadLine();

    } 

}