L Reg Nissan Micra?

What sequence are you using to enter the code?
Please post details.
If you have messed up entering the code several times, then the radio has to be switched on and left undisturbed for 12 hours. This is because of the security feature which doubles the time allowed between entries of code up to a maximum of just under 700 minutes. The first couple of attempts it`s 10 seconds , then the time increases rapidly.
Are you sure that you can`t see any seral numbers stamped on the side of the radio?

RegWorts
April 2008