Lost Radio Code for Renault Philips Radiosat 4000

[Tubby735]

Hi,
Can anybody help........
I've got a Renault megane 1.6 1998. The battery went flat, so recharged it.
But now the radio does not work....
When I first re-connect the battery the radio display showed CODE.
however I drove the car around for a few days with this showing (no music).
Now the word CODE has disappeared, and every time I switch the radio on all I see is the backlight of the display come on.
NO CHARACTERS..........

Radio Details:

Philips radiosat 4000
Ser No: RN449FV4140458
7700 426 414 ---
9022 214 49624