The publisher can sue the distributor for having negligently, or unreasonably carelessly, lost $15k of inventory entrusted to it: if the distributor was at fault (e.g. it was not in fact stolen by a 3rd party not under the distributor's control, with the theft not due to a lack of reasonable security), but rather was because of the carelessness, etc. of the distributor, the distributor is liable for the loss. A lawsuit is the only way to recover money in a case like this, if the distributor will not voluntarily repay.