answer: #Person2# blundered up a watch under the sofa and #Person1# tells #Person2# it's #Person1#'s watch.
documents: #Person1#: Is this watch yours?
  #Person2#: No, it isn't mine. I blundered upon it under the sofa. Do youknow whose watch it is?
  #Person1#: Let me have a look. It's mine. I have been looking for it, but just cannot find it. It's present from my father.
  #Person2#: Well, here you are. Remember to put it in a proper place.