IPhone can't connect to iTunes?

I still have iOS 9 on my iPhone SE, but everytime I tried downloading an app it said can't connect to iTunes, I tried to sign out and sign back in but I couldn t. Now everytime I try to sign back in it says can't connect to iTunes. I can still go on other apps like Twitter, so I know it's not my Wi-Fi, I also just changed my payment details in case that was the problem. I can't sign in to my iTunes even on my laptop. Nothing seems to be working. Any ideas?

Is my audio jack broken on my iphone?

Today, I plugged in my earbuds and heard no sound on it. My earbuds are not broken because I plugged them into another phone and it worked. When I plug it into my iphone 5 however, no sound comes out. The phone detects that it is plugged it. I tried to use an air cleaner to clean the jack but I was still unablr to hear anything. (My speakers still work) What do I do?

Is there a way to get sprint to let you upgrade early from a 2 year contract?

I have 2 iPhone SE's I got with sprint for free with a 2 year contract. It will be exactly a year i've had the contract in june this year and my contract does not end until june 2018. I've been having problems with the phone getting over heated and shutting off. I want to uprgrade to a iPhone 7 with financing. Everytime I call they tell me with a attitude to either wait another year or pay a $350 termination fee for each device.

IPhone 6s Plus won't download software update or apps?

My iPhone 6s Plus has been acting very odd the last 24 hours. I have attempted to download the software update. However it attempts to dowload it, but will shortly say Unable to Download. That s all it says-no explanation why. Also, I'm unable to download new apps from the App Store. It says the same thing, that it is not able to download at this time.
I have PLENTY of storage space. And I'm connected to private, strong Wi-Fi, so I'm at a loss to what the problem may be. I'm aware that you can update software through iTunes, however I only have a chrome book computer, and I believe iTunes is only available on windows or Mac.

Any suggestions on how to solve this problem will be greatly appreciated.