How do I get the lable synchronize button back?

I created a label document, saved it and closed out. Now that I want to edit again, the synchronize button is no longer visible. How do I get it back WITHOUT having to start over?

Neither in LO nor in OpenOffice 4.1.6 I was able to close the synchronise button. Have you moved it outside the window? When I tried I couldn’t do that, even a third or so remained in the main window. So what?