using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string hello = "<..,  <..  ,<..Hello, <..World, <..Hello World<.. , "; 

        var text = hello.Split(',')

            .ToList()

            .Select(x => Regex.Replace(x, "<..", "\n\r"))

            .Where(x => !string.IsNullOrEmpty(x))

            .ToArray();

        Console.WriteLine(string.Join(string.Empty,text));

    }

}