Detect whether Excel workbook is already open [closed]

Answer 1

If its open it will be in the Workbooks collection:

Function BookOpen(strBookName As String) As Boolean
    Dim oBk As Workbook
    On Error Resume Next
    Set oBk = Workbooks(strBookName)
    On Error GoTo 0
    If oBk Is Nothing Then
        BookOpen = False
    Else
        BookOpen = True
    End If
End Function

Sub testbook()
    Dim strBookName As String
    strBookName = "myWork.xls"
    If BookOpen(strBookName) Then
        MsgBox strBookName & " is open", vbOKOnly + vbInformation
    Else
        MsgBox strBookName & " is NOT open", vbOKOnly + vbExclamation
    End If
End Sub