Many women have areas of numbness inside their yonis. These areas are less sensitive due to energetical blockages from emotional trauma or tension. In order to fully enjoy sexual experience, your partner should be open, her energy flowing freely and without contraction.
The mind is easy to trick. If your partner has some areas where she doesn't feel anything at all, start to bring awareness to the spot, massaging it with more pressure, and at the same time play with other erogenous zones that you know she enjoys.
You can play with her breasts or clitoris or kiss her deeply; be playful and inventive. As you do this, your partner's brain will begin to connect the pleasurable sensations from other parts of the body to the numb area. The constant massage will also help the energy to flow.
This same technique can be used with painful spots. As you bring pleasure to other parts of her body, ask your partner to focus on connecting that pleasure to the painful area; slowly the knot will fade.