Sex toys can help you explore sensations on all parts of your body. Don't assume that if one part of your body feels a certain way everywhere else in that general area will feel the same way. There is variation in how sensation is experienced, but having reduced sensitivity doesn't have to mean reduced sexual response.
In areas of reduced sensation, toys that produce a light touch won't be very useful, while a vibrator can provide needed strength and stimulation. Many people explore sensation toys like paddles, whips, and floggers, which provide a more substantial sensation. Keep an eye on the area you are stimulating with decreased sensation it is easier to injure yourself with excessive pressure or rubbing without feeling it.