Please Help!!!!!!!

Question

I have a kenwood excelon kdc-x790. I had security code active,and recently had to take the battery out of my car.
When I put it back in the enter security code screen was displayed.
It has been so long sence I set the security code I can't remember the code.
Please help me with this matter,for my car audio system is the 2nd attraction to my car.but without it I'am afraid it does'nt hold for much compatition!!!!!!