ITunes music disappeared off PC?

My grandma uses a PC Windows 8.1. She uses iTunes for her music, but she doesn't update it, because she has an old iPod. She won't be able to use her old iPod with a new version of iTunes, according to the Apple store (please don't tell me that she needs a new iPod). So, she told me her music disappeared from her iTunes, a problem that I've seen on the internet after people have updated. She swears she hasn't updated her iTunes, and we can't find any Previous iTunes Libraries files to fix the problem, as many tutorials suggest. I see only one "iTunes Library.itl." Any suggestions for how to get her library back?