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Code:
Private Sub Worksheet_Change(ByVal Target As Range)
ActiveSheet.Unprotect Password:="aaa"
Dim rng As Range
Set rng = Target.Parent.Range("B16")
If Target.Count > 1 Then Exit Sub
If Intersect(Target, rng) Is Nothing Then Exit Sub
With Range("B19:E19")
Select Case Target.Value
Case "No"
.Value = 0
.Locked = True
Case "Yes"
.Value = ""
.Locked = False
End Select
End With
ActiveSheet.Protect Password:="aaa"
End Sub