Const сstrNumberFormat As String=strDollarFormat ' например

Option Explicit
Declare Function SendMessage32 Lib "user32" Alias "SendMessageA" _
    (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
    (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
    (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Const WM_LBBUTTONDOWN = &H201
Const WM_LBBUTTONUP = &H202

Sub ClickOnButtonInMsgBox()
Dim hWnd As Long
Dim x As Long, y As Long, z As Long

'Вместо AAA подставьте заголовок Вашего MsgBox-а
hWnd = FindWindow("#32770", "AAA") 'указатель на окно MsgBox

x = FindWindowEx(hWnd,  0 , "button", vbNullString) 'указатель на кнопку 'Ok'     (кнопку №1)
y = FindWindowEx(hWnd, x, "button", vbNullString) 'указатель на кнопку 'No'     (кнопку №2)
z = FindWindowEx(hWnd, y, "button", vbNullString) 'указатель на кнопку 'Cancel' (кнопку №3)

'Имитация щелчка левой клавишей мыши по кнопке 'Cancel' MsgBox-а
SendMessage32 z, WM_LBBUTTONDOWN,  1 ,  1  'нажатие на кнопку 'Cancel' левой клавишей мыши
SendMessage32 z, WM_LBBUTTONUP,  1 ,  1    'отжатие левой клавиши мыши на кнопке 'No'

End Sub

SendMessage32 z, WM_LBBUTTONUP,  1 ,  1    'отжатие левой клавиши мыши на кнопке 'No'

SendMessage32 z, WM_LBBUTTONUP,  1 ,  1    'отжатие левой клавиши мыши на кнопке 'Cancel'

Option Explicit
Declare Function SendMessage32 Lib "user32" Alias "SendMessageA" _
    (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
    (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
    (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
    
'Таймер высокого разрешения (в коде не использован)
'Declare Function SetTimer Lib "user32" _
'    (ByVal hwnd As Long, ByVal nIDEvent As Long, ByVal uElapse As Long, ByVal lpTimerFunc As Long) As Long
'Declare Function KillTimer Lib "user32" _
'    (ByVal hwnd As Long, ByVal nIDEvent As Long) As Long
'Dim TimerID As Long

Dim i As Byte
Const WM_LBBUTTONDOWN = &H201
Const WM_LBBUTTONUP = &H202

Sub ClickOnButtonInMsgBox(ByVal bytNcbn As Byte)
Dim hwnd As Long
Dim x As Long, y As Long, z As Long

'Вместо AAA подставьте заголовок Вашего MsgBox-а
hwnd = FindWindow("#32770", "AAA") 'указатель на окно MsgBox

x = FindWindowEx(hwnd,  0 , "button", vbNullString) 'указатель на кнопку 'Ok'     (кнопку №1)
y = FindWindowEx(hwnd, x, "button", vbNullString) 'указатель на кнопку 'No'     (кнопку №2)
z = FindWindowEx(hwnd, y, "button", vbNullString) 'указатель на кнопку 'Cancel' (кнопку №3)

'Имитация щелчка левой клавишей мыши по кнопке 'Cancel' MsgBox-а
SendMessage32 IIf(bytNcbn <  3 , y, z), WM_LBBUTTONDOWN,  1 ,  1  'нажатие на кнопку 'Cancel' левой клавишей мыши
SendMessage32 IIf(bytNcbn <  3 , y, z), WM_LBBUTTONUP,  1 ,  1   'отжатие левой клавиши мыши на кнопке 'Cancel'
If hwnd >  0  Then i = i +  2 
End Sub

Sub test()
Dim bytBN As Byte

Select Case i
    Case  0 : bytBN =  3 
    Case  2  To  4 : bytBN =  2 
End Select
ClickOnButtonInMsgBox ByVal bytBN
If i >  4  Then
    i =  0 
    Exit Sub
End If
Application.OnTime Now + TimeValue("0:00:01"), "test"
End Sub

for j= 1  to  3 
 x=MsgBox( "", vbYesNoCancel,"AAA")
 select case x
  case  6 :i= 1 
  case  7 :i= 2 
  case  2 :i= 3 
 end select
 MsgBox "нажата кнопка № " & i
next