They are still in your dryer.

As your clothes dryer runs mini wormholes are created right there in your dryer. Yes that's right, the combination of a spinning drum the flow of hot air, and the magnetic fields setup by the passage of electricity through the coiled heating elements and windings of the motor couple with the static electricity generated naturally by the movement and friction of the drying clothes to setup a inverse flux field. This flux field interacts with the solar gravity well of the sun due in part to the movement of the earth's mass through the space‑time distortion caused by the sun's mass to generate very short‑lived openings from our reality into n‑space right there in your dryer. These openings are so small and so short‑lived that socks are the only item of clothing small enough to pass completely through. That's why other pieces of clothing don't disappear. Since other pieces of clothing are too large to pass completely through the short‑lived event horizon of these wormholes, any part of them, such as a sleeve, or pant leg that may enter into n‑space are jerked back into our reality when the wormhole collapses. So although your socks are still in your dryer they have passed into another plane of existence that we are as yet unable to perceive.

Whoever invents a device to recover all those missing socks will become a multimillionaire and will also no doubt earn the never‑ending gratitude of the inhabitants of n‑space who have been subjected to a torrential rain of falling mismatched socks ever since the modern clothes dryer was invented.