how do i get code for my radio?

I had to disconnect the battery on my Renault Laguna, when i re-conected it i need the code. the problem is that previous owners must of had the same problem because on the radio there are 2 stickers from a de-coding company. so does this mean that i wont be able to use the original code if i pay to get it? can any one advise me what is the best thing to do & the best way to get the radio working again.