How to write code to restrict the copy-paste if sheet is having more than one drop-down?

hi timmu, if your data validation range is A1:D1, option with message and clearing content of the wrong validated cell value

Private Sub Worksheet_Change(ByVal Target As Range)

Dim rng As Range, cl

Set rng = Intersect(Target, Range("A1:D1"))

If rng Is Nothing Then Exit Sub

Application.EnableEvents = 0

For Each cl In rng.Cells
    If cl.Validation.Value = False Then
        MsgBox ("Please select the correct value from the Resource Designation drop-down in cell " & cl.Address(0, 0)), vbCritical, "Validation error"
        cl.ClearContents
    End If
Next

Application.EnableEvents = 1

End Sub