Have you had a bike stolen? While it’s probably not a very nice experience there may be some hope.
You can find the list of bikes that have been recovered by the police here
You’ll of course need some form of proof it’s your bike
Une pièce d’identité ainsi qu’un justificatif de la propriété du bien reconnu (facture, photographie, etc.) seront exigés pour la restitution.
So the bill for it, possibly a photograph of you with your bike may suffice.