ONLY the maker of that radio have access to the key codes AND the serial numbers.
First step: Ask the person who sold it to you.
If he can't give you that code, there is a good chance that it's a stolen unit.
Second step. If the seler can't give you the code AND you can realy say that it's NOT a stolen device, OR it's the radio that came with your car and you lost the code:
Comunicate with the maker or go to it's web site.
ONLY the maker of that radio can give you the required codes.
Electro, May 2013