Well, since you have reinstall the OS on your pc, you have wipe all informations store in the iTunes and also all your previous backup files. Those stuff purchased on iTunes can be download again and for free, "musics, books, videos, apps" the musics which was present in your iTunes but wasn't purchased from the iTunes will not show up until you add them to your iTunes library from your music folder on your computer or wherever you store them. As for your photos, except those present on your phone and on your storage device like USB disc or in partition on your computer, you will not be able to recover any other photos/videos, they are usually saved in a special iTunes folder in your computer, but reinstalling your computer OS certainly wipe them out from your computer already.