I bought a car cd

Question

I bought a car cd player from a friend...it came from his 306 pegeout .....i then put the cd player into my car and punched in the secuirty code and all was fine... 2 years on I got a flat battery and do not know the code.my friend who i purchased the car from has gone o/s and sold the car I have no way of get the code ..is there a way to activate the cd player with out the code