how can i fix my nissan almera cd/radio code?

Hi!
I bought a nissan almera and the cd/radio dosen't work.When I switch on the radio show me on the screen "wait" and "secure".I can't press anything and I don't know the code.Can you help me,please?serial no:cl052910033412 model no.:pn2424m nissan part no.:28185 bn321
Thank you!
Zoltan