Why do socks always disappear?
Humorously: Unfortunately the combination of heat and rotation of the dryer drum creates a vortex that allows the socks to be stolen by one-footed aliens from another galaxy. It is a myth that dryers eat socks, as they can't have that much fiber. Another explanation: Because of the evil sock-stealing Gnomes! A sock troll comes into the house at night and steals them from either the sock drawer or the dryer.
Alternate explanation: The dryer opens a time-space distortion similar to that found in women's purses. Like keys in a purse, the socks are kicked forward to next Tuesday, at which time they will re-appear. Since we are more apt to be looking for keys next Tuesday than socks, their return is less often noted, but the fact that lost keys inevitably turn up in the same purse from which they disappeared is proof of the phenomenon.
Factually : They gather static in the dryer and then stick to other items like shirts. If you go through your closet and look inside shirts/pants that were in the dryer, you will find your socks.