Hello and thank you would have been welcome when you ask for help.
That being said, there is no way to retrieve a missing pincode as far as I know.
Things you can try:
– if your device came with papers, look for a 4 figure number handwritten somewhere.
– If your friendly with a B&O dealer, talk with him to see if he agrees to help you.
– Talk with seller. It may be impossible but it should be more possible than guessing the right pincode out of the blue.