1. You made a seplling mistake.
  2. The page you were looking for only ever existed in your mind, like unicorns.
  3. You have a secret liking for 404 pages we will not be telling anyone about.
  4. We sent you here by mistake which was very silly of us. We are sorry and would love to hear how this happened
  5. Some other page sent you here which seems to be out of our control.