Recovering a Windows CD Key from Bootcamp Partition

So, before you disregard this thread and say "hey, buddy, shouldn't you be contacting Microsoft support about this sort of issue?" just know you'd be completely right if I hadn't already contacted them and being told that they can't do squat since my issue is on an apple machine. Yay.

So, just recently, my computer (I should mention I was running under the windows bootcamp partition) was running slower than usual. This usually isn't much of an issue since i'm using an older 2011 macbook pro using bootcamp, and a restart solves the issue nearly 100% of the time. You know, the ol' "turn it off and on again" solution. But this time, windows booted up into chkdsk, which, again, isn't much of an issue usually since this has always sorted itself out and I boot up just fine after chkdsk does its thing. Except this time, something somewhere went wrong and after chkdsk finished, I am no longer able to boot into windows at all. No safe mode or any variation thereof, and the startup fixing utility that I've started into a couple of times doesn't do the trick, and neither does restoring to a old restore point. So, my next step was to nuke everything and reinstall windows. Except, I don't have my old install disk from years ago anymore, and since I don't have another PC accessible to me, I can't download an iso to burn since I don't have a key. I know there's a way to get that key from my dead windows partition if I could boot up into it, but otherwise, I really need that key, and I'd prefer to not pay to get a new one.

Does anyone know if I need to buy a new windows key or if there is a way to recover that key from my bootcamp partition while booted up into the mac side?