Change keyboard language when application not in focus

Question

I am using SendKeys.SendWait to send keyboard keys to active window and in case the keyboard language is non English I want to change the keyboard language:

     var currentInputLang = InputLanguage.CurrentInputLanguage;
     var culture = currentInputLang.Culture.Name;
     
     var lang = InputLanguage.InstalledInputLanguages.OfType<InputLanguage>().Where(l
 => l.Culture.Name.StartsWith("en-US")).FirstOrDefault();
     if (lang != null)
         InputLanguage.CurrentInputLanguage = lang;

So this command works only if my WPF application is with focus, Any ideas how to change this keyboard language any way ?

UPDATE

XAML: This is how I start my view model class:

<Window.DataContext>
        <viewmodel:ViewModelBase/>
</Window.DataContext>

public class ViewModelBase : INotifyPropertyChanged
{
  public ViewModelBase()
  {
       MyCommand = new MyCommand(this);
  }  
}

My send keys command:

public class SaveCommand : ICommand
    {
        public ViewModelBase ViewModel { get; set; }

        public SaveCommand(ViewModelBase viewModel)
        {
            ViewModel = viewModel;
        }

        public void Execute(object parameter)
        }
            ChangeKeyboardToEnglish();
            
            // Send keys
            Thread.Sleep(500);
            SendKeys.SendWait(user);
            Thread.Sleep(150);
            SendKeys.SendWait("{TAB}");
            Thread.Sleep(150);
            SendKeys.SendWait(password);
            Thread.Sleep(150);
            SendKeys.SendWait("{ENTER}");
        }

        private void ChangeKeyboardToEnglish()
        {
            var currentInputLang = InputLanguage.CurrentInputLanguage;
            var culture = currentInputLang.Culture.Name;

            var lang = InputLanguage.InstalledInputLanguages.OfType<InputLanguage>().Where(l => l.Culture.Name.StartsWith("en-US")).FirstOrDefault();
            if (lang != null)
                InputLanguage.CurrentInputLanguage = lang;
            Thread.Sleep(250);
        }
    }