Are you running Photoshop CS6 Extended? Does it say "Extended" in Help > About Photoshop...
Photoshop CS6 Standard does not have 3D.
If you are running XP operating system the 3D options are not supported.
Did you buy a license for Photoshop CS6 Extended?
If so, and you are not getting Extended features, you'll need to call Customer Service, license number in hand, to try to get things worked out. No one here is going to be able to help you with the specifics of that.
Opps you said Win7.
This seems to be a probem with more than one user.
One of 2 things seem to work.
1. Deactivate and then reactivate PS.
2. If that does not work reinstall and it seem to fix things.
Thanks People great help I got there from all your thoughts ^_^