I had to replace the battery on my 02 Carrera, now My radio face is all dark and I can't insert the code, can I buy a radio with no code and use my code to reset the new replacement?

 

Codes are related to the serial number of the radio in most Becker radios of a certain era.

No reason a battery replacement alone would cause a radio not to display something. Does everything else on the car work?

So either something else happened to cause a disconnect of the wiring or something very unusual happened.

Have a matching model Becker radio with a serial number and you can get the code that matches it. More on radio codes here. But I doubt the radio is the problem.