|Sounds like technical repairs are necessary as those buttons should work whatever mode your camera is in, you cannot accidentally "lock" them.|
if the camera warranty has expired, repairs are likely to be quite expensive since it has to be returned to Nikon (unlike old film cameras you can't just take it to any camera repair shop).
If, however, it's still covered by warranty, well it's a no-brainer, contact Nikon and request repairs under the terms of the warranty. The most it will cost you is one-way postage.
message edited by phil22