using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = @"

            [

              {

                ""children"": [

                  {

                    ""children"": [

                      {

                        ""children"": [],

                        ""text"": ""Child node 2.txt"",

                        ""isFolder"": false,

                        ""id"": ""1childnode2.txt"",

                        ""itsPath"": ""C:\\Users\\pandyapa\\Root node\\Child node 2.txt"",

                        ""type"": ""itsfile""

                      }

                    ],

                    ""text"": ""Child node 1.txt"",

                    ""isFolder"": false,

                    ""id"": ""0childnode1.txt"",

                    ""itsPath"": ""C:\\Users\\pandyapa\\Root node\\Child node 1.txt"",

                    ""type"": ""itsfile""

                  },

                  {

                    ""children"": [],

                    ""text"": ""Child node 2.txt"",

                    ""isFolder"": false,

                    ""id"": ""1childnode2.txt"",

                    ""itsPath"": ""C:\\Users\\pandyapa\\Root node\\Child node 2.txt"",

                    ""type"": ""itsfile""

                  },

                  {

                    ""children"": [],

                    ""text"": ""Child node 3.txt"",

                    ""isFolder"": false,

                    ""id"": ""2childnode3.txt"",

                    ""itsPath"": ""C:\\Users\\pandyapa\\Root node\\Child node 3.txt"",

                    ""type"": ""itsfile""

                  }

                ],

                ""text"": ""Root node"",

                ""isFolder"": true,

                ""id"": ""3rootnode"",

                ""itsPath"": ""C:\\Users\\pandyapa\\Root node"",

                ""type"": ""default""

              }

            ]";

        List<Node> nodes = JsonConvert.DeserializeObject<List<Node>>(json);

        var idToFind = "2childnode3.txt";

        var node = nodes.SelectMany(n => n.DescendantsAndSelf())

                        .Where(n => n.Id == idToFind)

                        .FirstOrDefault();

        if (node != null)

        {

            Console.WriteLine("ItsPath: " + node.ItsPath);

        }

        else

        {

            Console.WriteLine("Not found"); 

        }

    }

}

​

public class Node

{

    public Node[] Children { get; set; }

    public string Text { get; set; }

    public bool IsFolder { get; set; }

    public string Id { get; set; }

    public string ItsPath { get; set; }

    public string Type { get; set; }

    public IEnumerable<Node> DescendantsAndSelf()

    {

        yield return this;

        if (Children != null)

        {

            foreach (Node child in Children)

            {

                yield return child;

            }

        }

    }

}

​