Private Declare Function ActivateKeyboardLayout Lib "user32" (ByVal HKL As Long, ByVal flags As Long) As Long

Private Const KBL_RU As Long =  68748313 
Private Const KBL_EN As Long =  67699721 

Private Sub Command1_Click()

    ' Переключить на русский язык
    Call ActivateKeyboardLayout(KBL_RU,  0 &)
    
    ' Переключить на английский язык
    Call ActivateKeyboardLayout(KBL_EN,  0 &)

End Sub

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function ActivateKeyboardLayout Lib "user32" (ByVal HKL As Long, ByVal flags As Long) As Long
Private Declare Function LoadKeyboardLayout Lib "user32.dll" Alias "LoadKeyboardLayoutA" (ByVal pwszKLID As String, ByVal flags As Long) As Long

Private Const HWND_BROADCAST As Long = &HFFFF&
Private Const WM_INPUTLANGCHANGEREQUEST As Long = &H50
Private Const WM_INPUTLANGCHANGE As Long = &H51

Private Const KBL_EN As String = "00000409" '1033
Private Const KBL_RU As String = "00000419" '1049
Private Const KLF_ACTIVATE  As Long = &H1

Private Const INPUTLANGCHANGE_SYSCHARSET As Long = &H1
Private Const INPUTLANGCHANGE_FORWARD As Long = &H2
Private Const INPUTLANGCHANGE_BACKWARD As Long = &H4


Private Sub Command1_Click()
    Dim hKBLang As Long
    
    hKBLang = LoadKeyboardLayout(KBL_RU, KLF_ACTIVATE)
    
    ' Переключить на русский язык
    Call ActivateKeyboardLayout(hKBLang,  0 &)
    SendMessage HWND_BROADCAST, WM_INPUTLANGCHANGEREQUEST, INPUTLANGCHANGE_SYSCHARSET, hKBLang
    
    ' Переключить на английский язык
    'Call ActivateKeyboardLayout(KBL_EN, 0&)

End Sub