How do you find a book if you dont know the name but you know how the cover looks like?

Can you remember anything at all, such as the author or the Words on the back? If not, what does the cover look like? I may be able to help you- or maybe someone else can. on the cover is a girl maybe, looking threw binoculars. The book is about a girl that survivse some kind of fallout, and she's living on her on. I can go in more detail if it would help.