Forum:Reset Item

I found a Dark Lance in the underworld, in a chest, and later took it out of my inventory, placing it on the floor in my house. The next time I was back in the game, it disappeared. I read that items sometimes reset/disappear this way, and I was wondering if this means that it's completely gone from my world, or if had reset and is somewhere else in the world. I was kicking so much ass with this weapon, and am really bummed out that it's gone. Any help would be fantastic.