Hello Alberto Italy. Welcome to the NS Community.

I'd have to ask you to translate your message, we can only help you in Dutch or English! 

See https://service-formulieren.ns.nl/ns/en-customer-service-lost-and-found-items-report-lost-item

Friday evening on the 18.53 o'clock train that left from Amsterdam Zuid to Hoopddorf, getting off in Schipol I left on the seat of the first wagon in 2 class my black backpack Notino brand containing eyeglasses and sunglasses, dispenser for asthma, gloves, beige scarf, a Go pro 10 with some accessories, bread and wafers, it was my first and only wedding anniversary trip in Holland, I realized I forgot it right away but unfortunately the train is without starting again. I would be very grateful if someone could give me information or if they had taken it, I made the report immediately to the police and the lost and found with no result, I would like to get back at least the personal belongings and photos that were in the memory card of the camera.

If that's the case I would advise following Robert B's link! 

I had already communicated everything to the police as soon as the fact happened, who replied that the train had arrived at the warehouse and no one, not even they had access to the wagon and to report to the post and found of the railways.