Radio code for 2003 plate Ford KA?

My radio in my ford KA won't work, it says it needs a code. It is a 2003 plate. On the radio it says 6000 CD RDS E O N

The serial number is M054406

Can anyone help me with this please?!

Added (1). also, after I have typed in the code, what button do I press on the radio?

This is an anti-theft code which must be entered if the radio loses power (also happens when teh battery cables become lose or are removed during maintenance)

Call the place you bought the car. Or, you could pay a service to get you the code. Like this one
http://www.radio-code.com/

Your code for that serial number is 0406