' This function checks to see if a file is open or not. If the file is
' already open, it returns True. If the file is not open, it returns
' False. Otherwise, a run-time error occurs because there is
' some other problem accessing the file.

Public Function IsFileOpen(filename As String) As Boolean
    Dim filenum As Integer, errnum As Integer
    On Error Resume Next   ' Turn error checking off.
    filenum = FreeFile()   ' Get a free file number.
    ' Attempt to open the file and lock it.
    Open filename For Input Lock Read As #filenum
    Close filenum          ' Close the file.
    errnum = err           ' Save the error number that occurred.
    On Error GoTo 0        ' Turn error checking back on.
    ' Check to see which error occurred.
    Select Case errnum
        ' No error occurred.
        ' File is NOT already open by another user.
        Case 0
         IsFileOpen = False
        ' Error number for "Permission Denied."
        ' File is already opened by another user.
        Case 70
            IsFileOpen = True
        ' Another error occurred.
        Case Else
            Error errnum
    End Select
End Function

Sub ChiudiWbAperti()
Application.ScreenUpdating = False
For Each wb In Application.Workbooks
  If wb.Name <> ThisWorkbook.Name Then wb.Close True
Next
End Sub