using System;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""CommomData"": {

                ""DateTime"": {

                  ""Year"": 2019,

                  ""Month"": 3,

                  ""Day"": 11,

                  ""Hour"": 14,

                  ""Min"": 1,

                  ""Second"": 29

                }

              },

              ""Status"": {

                ""Mode"": ""Test"",

                ""Loc"": ""Test""

              }

            }";

        var mode = FindValue(json, "Mode");

        Console.WriteLine(mode);

    }

    private static string FindValue(string json, string name)

    {

        var token = JObject.Parse(json).SelectToken("$.." + name);

        return token != null ? token.ToString() : null;

    }

}

​