Recovering old CDkeys?

I badly need to reinstall my windows. Various reasons.

The problem is that when I moved out from my parents about a year ago, a box with all my old computer boxes, Games, flash :’( and etc. Ofcourse all the cdkeys were lost. Now some games I dont care about since I dont really play them.

So anyone know how to recover CDkeys? Most importantly for BF2 and flash ofcourse.

I found a couple of sites refering to a regkey as the CDkey. I located it but its a maybe 40-50 long serial. Which I guess the cdkey cant be =(.

Thanks alot for any help.