I tried enabling 3D but it doesn't really do anything, it just makes the screen go fuzzy.
The other 3D setting makes two copies of the same screen, one on the left and one on the right.
I thought people said Crysis 2's 3D was one of the best...

(and my Nvidia stereoscopic 3d option has somehow disappeared too...)

First off, what kind of 3D solution are you using in general for gaming in 3D? Interlaced? Side by Side? Anaglyph? Shutter? Or NVIDIA 3D VISION?

Interlaced may work with generic 3D monitors that aren't "NVIDIA 3D VISION READY". But there isn't any official support by CryTek/NVIDIA on these monitors, obviously. You'll have to refer to whatever support and documentation that comes with your generic solution if this is what you have.

Side by side. I haven't seen any side-by-side based 3D monitors in a very long time, and it's been years since I've used this as a solution, so forgive me for not knowing.

NVIDIA 3D VISION? This is easy. Quit out of the game, download the latest NVIDIA 3D VISION driver from the NVIDIA website and install it. BE AWARE that the NVIDIA 3D VISION drivers are NOT THE SAME THING as the NVIDIA Display Drivers. You MUST download the separate NVIDIA 3D VISION drivers to run the game in "DRIVER" 3D mode.

Hope this helps. NVIDIA Stereoscopic 3D Option shouldn't be relevant to making Crysis 2 run in 3D. And you heard correctly, Crysis 2's 3D is one of the best I've experienced. Add in 5.1 surround sound and... wait, surround sound is buggy on the PC version. Well, besides that! Crysis 2 runs amazing in 3D! Max out your Depth Amount when you can.

Also, just in case you werne't aware of it already, you MUST have NVIDIA 3D VISION glasses to run the game in Driver mode, obviously.

A while ago I used to be able to press Ctrl+T in a game to enable Blue/Red 3D but now I can't.
And the Crysis 2 3D is just blurry, no colour changing at all

I don't think Crysis 2 supports anaglyph, which I'm assuming is what you're referring to for blue/red 3D. I could be wrong though. CTRL T is an old NVIDIA S-3D gimmick from many months (possibly years?) ago, I would recommend getting NVIDIA 3D VISION. It comes with a separate physical IR emitter that you press a button for, and it auto-configures the game to operate at the best 3D settings (obviously can be changed later in NVIDIA Control Panel)

Ah, so it's different? ok thanks for the info

Good luck! I bought my NVIDIA 3D Vision kit from TigerDirect for $120. Free shipping, no tax when I got it.

Also, correction: 3D settings aren't changed in the NVIDIA Control Panel anymore, they're changed directly in game using the Depth Switch from the back of the NVIDIA IR Emitter device. (To my understanding, again, I could be wrong)