Option Explicit
Private Sub Worksheet_BeforeDoubleClick(ByVal c As Range, Cancel As Boolean)
Cancel = True
Select Case c.Address
Case "$A$4": Rows("5:6").EntireRow.Hidden = Not Rows("5:6").EntireRow.Hidden
Case "$A$7": Rows("8:14").EntireRow.Hidden = Not Rows("8:14").EntireRow.Hidden
Case "$A$15": Rows("16:18").EntireRow.Hidden = Not Rows("16:18").EntireRow.Hidden
Case "$A$19": Rows("20:21").EntireRow.Hidden = Not Rows("20:21").EntireRow.Hidden
End Select
End Sub