Good question! As trivago is a price comparison website, we are not involved in the booking process, we just find your ideal hotel for the ideal price. We display and compare different offers from multiple booking sites, but are not a party to any hotel booking agreement between you and the site or hotel you book with. As a result, we keep no records of transactions made through the booking sites, and unfortunately cannot access your booking to make any changes or provide information on it.
Luckily, the booking site can help you with this. If you need to get in touch with the booking site you used, most contact information can be found at the bottom of your booking confirmation. Alternatively, booking sites will have a contact page, where you will likely find all contact details including direct phone numbers to the booking site’s support center.