iphone 6s won't connect to itunes
So I just got an iPhone 6s for Christmas and it's all set up (surprisingly be me?? Somehow??). But now I'm trying to listen to my music and I can't get some of my songs. Before, it would show the whole album (that I bought, in full, months ago) and only some of them would play. The songs that I could listen to had a little symbol of a phone with a check mark through them, the ones that refused to play and would just skip past did not have that symbol.
Based on another suggestion on here I tried going to iTunes on my computer and going to Store>Check for available downloads and that got me the music back onto my laptop, but I still can't get it on my phone.
Whenever I try to connect my phone to my laptop it just says "The iPhone "iPhone" cannot be used because it requires a newer version of iTunes. Go to www.itunes.com to download the latest version of iTunes." So I did this, and it now says I already HAVE the latest version of iTunes.
I want to scream.
At this point I just want to get the music that I payed my money for and be able to sync/backup my phone to my computer.
Please help.
iPhone 6s, iOS 9.2