If you believe the child was at fault, you have the right to sue his parents for the cost of the mirror: if you can convince a court that he was at fault, you can get a judgment for the cost to repair or replace. It is unclear, however, if the time lost from work (assume you will give up at least one day), plus the inconvenience, plus the cost of filing the suit (around $50-$60) is worth what you hope to get back.