I think there are three general things you can try.
First though, you may want to read this article about anorgasmia at the Mayo Clinic, it has some information and will let you know you are not alone with this problem.
If you haven't introduced a vibrator into masturbation or intercourse you can try this method, I think it works for many women. Hopefully you have an understanding partner, or just try it yourself. It doesn't replace your partner, just helps you, and that's a good thing. You can find them online or even in stores and drugstores now. Size, shape and color is your preference. There is an article on Health Central about these done some time ago, I think it is a bit flippant but may help you with these.
Talk frankly with your gynecologist about this problem, believe me, you are not the first with this problem, they have dealt with this more than once already. You need to make sure there is no physical problem, outward appearances are not enough to confirm the absence of a problem.
The third possibility can involve your gynecologist referring you to someone local who is trained to help with this type of problem if no physical cause is found. You don't need to live with this, but you have to be willing to try, and take doctors into confidence, but that's why they are there, to help with your health, and this is a health problem, with solutions.