Radio doesn't work for me

After changing the battery, the radio does not work for me a code but I can't find it, where I can find it

Greetings Nacho, in certain Fiats and Renault, they cannot be left without battery for a long time because radio, electric glass and rare occasions to the key. In one of your vehicle's user manuals, such a code is printed that you need, not all are the same, last appeal to request it in the concessionaire. What model is your vehicle?

It is a 2004 Seat Leon the problem in the user book does not come to me