How to log when windows service is being stopped by server restart c#

I want to handle when windows service is killed by task manager or by system restart.

I tried using below handler inside Timer_Elapsed method of the service timer

 public void Start()
    {
        AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
        _myTimer= new Timer(10000);
        _myTimer.Elapsed += OnElapsed;
        _myTimer.AutoReset = false;
        _myTimer.Start();
    }

  private void OnElapsed(object sender, ElapsedEventArgs e)
     {
                try
                {
                   _myTimer.Stop();
                   //Work
                }
                finally
                {
                    _myTimer.Start();
                }
     }

and even I have placed the same into Main() method of the console as I am using Topshelf for windows service.

 static void Main(string[] args)
    {
        AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
        var exitCode = HostFactory.Run(hostConfigurator =>
        {
            hostConfigurator.Service<MyService>(serviceConfigurator =>
            {
                serviceConfigurator.ConstructUsing(() => new MyService());
                serviceConfigurator.WhenStarted(MyService => MyService.Start());
                serviceConfigurator.WhenStopped(MyService=> MyService.Stop());
            });

            hostConfigurator.RunAsLocalSystem();

            hostConfigurator.SetDisplayName("MyService");
            hostConfigurator.SetDescription("MyService");
            hostConfigurator.SetServiceName("MyService");
            hostConfigurator.UseLog4Net();
        });
}


private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
        {
            File.AppendAllText(@"C:\Crash.txt", "Main Termination");
        }

In either scenario the handler is not getting called when I kill the windows service process from task manager or system restart. Even TopShelf is not logging "UnhandledServiceException" exit code.

I have searched for all possible ways but no luck. Could any one please help me in this.

Thanks