' Paste this code in Module
' for Demonstration purpose a timer has been setup to run the macro during locked mode


Private Declare Function SwitchDesktop Lib "user32" (ByVal hDesktop As Long) As Long
Private Declare Function OpenDesktop Lib "user32" Alias "OpenDesktopA" (ByVal lpszDesktop As String, ByVal dwFlags As Long, ByVal fInherit As Long, ByVal dwDesiredAccess As Long) As Long
Private Declare Function CloseDesktop Lib "user32" (ByVal hDesktop As Long) As Long
Private Const DESKTOP_SWITCHDESKTOP As Long = &H100




Public Sub setTimer()
Application.OnTime TimeValue("17:55:30"), "status"
End Sub

Public Function status()
Dim p_lngHwnd As Long
Dim p_lngRtn As Long
Dim p_lngErr As Long

p_lngHwnd = OpenDesktop(lpszDesktop:="Default", dwFlags:=0, fInherit:=False, dwDesiredAccess:=DESKTOP_SWITCHDESKTOP)

If p_lngHwnd = 0 Then
status = "Error"
Else
p_lngRtn = SwitchDesktop(hDesktop:=p_lngHwnd)
p_lngErr = Err.LastDllError

If p_lngRtn = 0 Then
If p_lngErr = 0 Then
status = "Locked"
Else
status = "Error"
End If
Else
status = "Unlocked"
End If

p_lngHwnd = CloseDesktop(p_lngHwnd)
End If
MsgBox status
End Function