Option Explicit
Dim s As String
Dim x As Long

'*******************************
Private Sub Command1_Click()
Dim i0%, i%
List1.Clear
x =  0 
s = Text1.Text
i0 = Int(Val(Text2.Text))
For i = i0 To Len(s)
    combo s, i
Next
End Sub
'*******************************
Sub Sm(AlreadyS As String, s As String)
Dim i As Integer
  If Len(s) =  1  Then
    List1.AddItem AlreadyS + s
    DoEvents
    x = x +  1 
    Label1.Caption = x
    Exit Sub
  End If
  For i =  1  To Len(s)
    Sm AlreadyS + Mid$(s, i,  1 ), Left$(s, i -  1 ) + Mid$(s, i +  1 )
  Next
End Sub
'*******************************
Sub combo(ss$, k%)
Dim i%, j%
If Len(ss) = k Then
    Sm "", ss
Else
    For i =  1  To Len(ss) - k +  1 
    If k =  1  Then
        combo Mid(ss, i,  1 ),  1 
    Else
    For j = i +  1  To Len(s) - k +  2 
        combo Mid(ss, i,  1 ) & Mid(ss, j, k -  1 ), k
    Next j
    End If
    Next i
End If
End Sub