Warning before overwriting existing data in VBA - excel

Question

I have the below code that creates a pop-up when new data is pasted into the specified range (A15 : E33). What I would like is when the user attempts to paste data into the range the pop up shows up and if the user selects no the data isn't pasted, preventing accidental overwrite.
Currently when the user selects no all it does is prevent cell B2 from being timestamped.
Thank you in advance for your help
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$15:$E$33" Then
Dim answer As Integer
answer = MsgBox("You are about to overwrite existing data, would you like to continue?", vbQuestion + vbYesNo)
If answer = vbYes Then
Range("B2") = "=NOW()"
Range("B2").Copy
Range("B2").PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
:=False, Transpose:=False
Range("a15:e33").Select
Else
MsgBox "Cancelled"
End If
End If
End Sub

Answer 1

Your code cannot know about your intention to paste in a specific range...
The above code is an event, being automatically triggered when the pasting has already been done. What you can do is using Application.UnDo:
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.address = "$A$15:$E$33" Then
Dim answer As VbMsgBoxResult
answer = MsgBox("You are about to overwrite existing data, would you like to continue?", vbQuestion + vbYesNo)
If answer = vbYes Then
Application.EnableEvents = False 'to avoid the event being triggered again...
Range("B2") = "=NOW()"
Range("B2").Copy
Range("B2").PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
:=False, Transpose:=False
Range("a15:e33").Select
Application.EnableEvents = True
Else
Application.EnableEvents = False 'to avoid the event being triggered again...
Application.Undo
Application.EnableEvents = True
MsgBox "Cancelled"
End If
End If
End Sub