Look at your paperwork from when you got the car like Gen says, most people write the code down in at least some obvious spot. If not you will need to either take the car in to BMW dealer and verify your vin and they can pull the code or take the radio in and again verify you are the owner. That is messed up stuff for such old radios but it is what it is. No hacking it.
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy