Did you ever lose a sock, Like the identical twin of the sock just vanished into thin air never to be seen again? How? Why? What would possibly cause a sock to just up and leave? It's an impossible question to answer without proof, but I have an idea what the possible answer might be, although you may not like it or believe it to be true.
I believe socks disappear to an alternate reality where their sock King sends out a call, a ring a bell humans can't hear, to come home to the motherland, a place of cleanliness and hope, a beautiful landscape covered in cotton and dryer sheets, a peaceful world that is under attack by the hopeless angered disowned socks, the socks of darkness, the socks with rips and holes, the ones that were thrown into the trash. The socks with holes have grown tired of the high and mighty king sock and have decided to wage an endless war against them, decimating their cotton kingdoms.
The Sock King must enlist the help of the socks of our world to fight the evil holed socks, the sad used socks of yesterday that were thrown into trash cans left alone to wither away in depression have decided no one should have happiness, not anymore.
Our socks that disappear are tributes, heroes without names who sacrifice their happiness with their soul mates to fight for their land and country. We should think of them and give them a moment of silence for everything they do for their people.
Either that, or there is an Island of misfit socks that are waiting to be found and used again. Where do you think the lost socks go?