What is the code for my Ford Ka's Radio?

Hi, I have a problem with my Ford KA's Radio. I took it into the garage last week because it had a clutch problem, they had to disconnect the battery so now my radio is asking me for a code. My car is second hand, I didn't get a manual, so I don't know what the code is. I have a E-O-N radio (whatever that is) and the serial no. is M011971. Can you help please??