First thing is to uncheck the box under:
   Tools | Options | Startup | Special keys

Then set the KeyPreview property of your form to Yes.
Use the *form's* KeyDown property to handle all keystrokes (e.g. not
allowing Alt+F to get to the File menu). It's event procedure will look like
this:

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
   Call LimitKeystroke(KeyCode, Shift)
End Sub

That calls a function that you store in a standard module, so that you can
call it from all your forms:

Function LimitKeystroke(KeyCode As Integer, Shift As Integer)
   Select Case KeyCode
   Case 96 To 111, vbKeyBack, vbKeyTab, vbKeyReturn
       'Allow numeric keypad, backspace, tab, and enter.
   Case Else
       KeyCode = 0 'destroy every other keystroke.
   End Select
End Function

See help for KeyPress event.  Also, help for KeyPreview property.
Basically, you'd set the KeyAscii return value to 0 for any keys you want
ignored, i.e., (air code follows)

 Select Case KeyAscii
   Case 65 to 83, 85 to 255  'alpha keys and upper ASCII
       keyAscii = 0
   Case 48 to 57, 42, 43, 45, 47  'These are numeric and math
operators...do nothing
   Case 13, 8, 10  'Carriage return, backspace, line feed...do nothing
   Case 84     'T...do nothing
   Case Else
       KeyAscii = 0
   End Select

You'd also need to do something in KeyDown event to trap function keys and
the like.