I lost my book!!!!!!?

i lost my book for english cl and i need to have it done by monday and today is friday and didn't even start the book and its like 300 pages!! idk what to do cuz i got the book from a public library and i lost it in school. i went to like place i thought ileft itt and the teachersaid shee didn'tt see it and i wasPOSITIVEE that it was in there!! so id kwhatt to do!!!! help plz!! or if u dont know what i can do, can u tell me a wedsite or something for free with an online book.