PS CC requests serial, can't find .hosts file on Win 8.1

Well, that's pretty much it.
I can't use Photoshop because it keeps bugging me with "enter serial". I looked about for advice, and did all the most commonly suggested things (language, security settings etc.) BUT when it comes to resetting the .hosts file --well, damn. I cannot find it anywhere. Or, to be more precise, there is one file named .hosts in my system32/etc folder, but when I open it, all I get is a a few lines of text explaining that "This is a sample HOSTS file used by Microsoft TCP/IP for Windows" and instructions on how to edit such a file. There are no actual host entries, or anything else for that matter, so I can't do anything with it.
So... what am I missing? I haven't had Windows 8.1 for long and I'm not all that familiar with it yet. It's just so damn irritiating when I can't do any work, and can't use the software I'm paying for