Go through all of your paperback books and separate those that are bent or out of shape. Make a stack of these books and put them to the side. Be sure to go through your paperback books carefully so that you can flatten as many of them as you can to save yourself some valuable time and effort.
Go through your bent paperback books that you separated earlier and try to flatten out the pages that are bent. Most of the time, it is usually the corners that are bent for marking your place while reading. Try to go through as many paperback books as you can and straighten all the pages before proceeding to the next step.
Use weight to flatten:
Put your bent paperback books under large heavier books to put some weight on them. This pressure will hopefully flatten your books nicely. Try to keep the bent paperback books under this weight for an extended period to help flatten all of the pages. If you cannot find large heavy books, then you can always use something else like a few bricks or something else that flat and heavy.
Stack books together:
Put your bent books between stiff hardcover books on a shelf. Try to cram as many books as you can between stiffer books on the shelf. This will flatten your paperback books and hopefully bring them back to shape.
Avoid bending pages:
Try to avoid bending the pages while reading your paperback books. It is a habit that we all have while reading and trying to mark our place in the book. If you use a bookmarker instead, this will help keep your paperback books in good shape.
Box books tightly:
You can cram all of your bent paperback books in to a small box and this will put pressure on the books to help them flatten. Remember to keep them in the box for as long as possible to help them get flat.