Lost SN

[Carlyrosk]

Hi!

I'm not sure if this is the right section to put it in, and I couldn't find another post about this, so I just put it here.

A few years back, my dad got me Amnesia as a Christmas gift from Amazon. It was a CD with a serial number in it on a piece of paper.
I had to get my laptop fixed because the screen was internally broken, and Amnesia now requires a serial number, but I can't find the case anywhere. Does this mean I have to buy a new game if I can't find it? Or is it possible to get a new serial number?