I Don't Get It!

So, today after my exam, I went to go and pick up my lab book and it wasn't there. Everyone else's book was there, not mine. I went to talk to my TA, but she wasn't there, but I ended up running into my professor, and he had just e-mailed me because he thought something weird was going on with my lab book. He didn't think that I just wouldn't hand it in. So, yeah it's gone. And I'm ticked off. I guess someone might have accidentally taken it, but that really doesn't make much sense, there's only 9 people in the class. And I don't know why anyone would take it. Who wants a stupid lab book? I'm really angry because that's the hardest physics class I've ever taken, and I worked so hard. I wanted to keep that lab book, I was really proud of it. So now I have to go back to school, because my professor said I should talk to my TA, so there goes that nap I had planned.