If you're not too sold on the idea of a desert planet, a thick rainforest jungle would do the trick. Just like in Vietnam, the dense forest would render the long-range and even beyond-visual-range capabilities of modern weapons nearly on pair with melee weapons, while the wet weather would quickly take a toll on nearly all kind of modern technology, even supposedly water-proof. Rain and trees would also hamper all kind of communications.
EDIT
As you want it to be a desert, I'd go with @nzaman answer (I had upvoted it even before writing my own answer). An idea I have had as an afterthought: if the gravity is not too high but the air pressure is similar to Earth - so that it is normally breathable by humans - you could have constant dust clouds in your desert.
The dust would create a fog reducing visibility to just a few meters away. In these conditions, firearms are not very useful - they need ammo, the dust spoils them quickly, and are not that good in very close combat, for they lack in stoping power (you can shot someone and he still can cut off your head with his sword before dying) and are prone to friendly fire in the mayhem of a melee. Communications would work unless you add the magnetite nzaman suggested, but it's not that useful either. How do you communicate your position when you can't see where you are? With no GPS, which depends of a network of already deployed satellites, the only way to find you is with triangularization of your signal, but you need to keep on transmitting to do that, and batteries run off - and you can't recharge them.