As a teacher, I refuse to spend anytime looking for lost property. If I pick something up and it has a name, I'll return it, but don't come to me and tell me your child has lost X (for the tenth time this term) and expect me to spend days looking for it.
I had a mother this year that has finally given up asking. First term she wanted me to put all the students in the gym with their hats and go and check every name label (all 900 students!) because someone had 'obviously' stolen her son's. I refused. (Hat was eventually located in his tub). Then the second term she wanted me to put all the kids in the hall because her son had lost his unlabelled jumper (again), and to take everyone that didn't have a name off the child and put them in a pile for her to check if she could identify the one belonging to her son. I refused. No idea about the outcome of this one as I refused to deal with her again after she complained to the Principal about my refusal to spend a couple of hours checking every jumper on every child in the school. Principal laughed her out of the office.