What is the ruling on stealing food from the school canteen at the age of seventeen, without knowing the value [of the stolen items] or the owner of the canteen, and how can one repent from that?

The questioner must return the value of the stolen food to its owners, estimating the value so that it does not exceed it, and delivering it by any possible means. If the cafeteria is still owned by the school or a specific person, the money should be returned to them. However, if its owner has died or abandoned it, she should strive to search for the owner or their heirs to return the right to them. If that is not possible, she should give the value in charity on behalf of its owner.