Use ThisWorkbook
which will refer to the original workbook which holds the code.
Alternatively at code start
Dim Wb As Workbook
Set Wb = ActiveWorkbook
sample code that activates all open books before returning to ThisWorkbook
Sub Test()
Dim Wb As Workbook
Dim Wb2 As Workbook
Set Wb = ThisWorkbook
For Each Wb2 In Application.Workbooks
Wb2.Activate
Next
Wb.Activate
End Sub