Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
ActiveSheet.Unprotect Password:="."
If Not Intersect(Target, Range("K2")) Is Nothing Then
Cancel = True
If Target = "" Then
Target.Formula = Date & Chr(10) & Format(Time, "HH:MM")
Else
Target = ""
End If
End If
ActiveSheet.Protect Password:="."
End Sub