Lost school library book?

Okay so last year I lost a book from my school's library. I thought, no sweat, they'll for get about it next year. Well, it turns out that they didn't. I am now in grade 9 (my last year in this school). They sent around a thing to the homeroom teachers saying who had late books and everything. It had my book on it. The homeroom teacher said something like they could not give you your report card if they felt like it because of it (like if you don't replace it or something). Is this true? I wouldn't really mind buying a new one, but money is pretty tight at my house right now, and my parents would be really mad. So what can I do?