13 years
How many days before your reservation did you cancel? What was the cancellation policy on that particular hostel? While 24 hours is the default, I think properties can put 48 hours and perhaps even longer. This info is given at the bottom of the "info" section for the hostel.
You can try contacting hostelworld through email and phone calls, but you may have a long battle ahead of you to get your money back.
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