In short: a refundable rate can usually be cancelled for free until a stated deadline. A non-refundable rate usually can't. If the hotel or organiser cancels on you, you are generally entitled to your money back.
1. Check your rate and deadline
Your confirmation shows the cancellation policy that applies to your booking. Take a screenshot when you book, since policies shown later may differ.
2. Know who you booked with
- Booked directly with the hotel: the hotel handles cancellations and refunds.
- Booked through a platform (an online travel agency): start with the platform, which processes the refund under the terms you accepted.
3. If the provider cancels
When a hotel, host or organiser cancels your booking, you should get a full refund of what you paid for the stay. Ask in writing if it doesn't arrive.
4. Package holidays
In the EU and the UK, package holidays (for example flight plus hotel booked together) have extra protection. If the organiser cancels the package, you're entitled to a full refund.
5. Travel insurance
Insurance may cover cancellations for covered reasons such as illness. It usually doesn't cover a change of plans. Read the policy wording, and claim promptly with documents.