Utilize below/bottom examplified function as in below immediate window
quest:

? fileisopen("c:\data\ta\ta\ta\myfile.xls")
False

'= VBA function outlay
Function FileIsOpen(ByVal FileName As String) As Boolean
Dim i As Integer
   i = FreeFile
   On Error GoTo ErrOpenFile
   Open FileName For Binary Access Read Lock Read As #i
   Close #i
   FileIsOpen = True
ExitHere:
   Exit Function
ErrOpenFile:
   Resume ExitHere
End Function

Krgrds,
Perry