If you are unable to connect to iTunes here are some things to try:

1. Make sure your iOS is up to date (Settings > General > Software Update)
2. Make sure your date, time and time zone are correct on your device (Settings > General > Date&Time)
3. Check your device restrictions (Settings > General > Restrictions)
4. Check and verify that you're in range of a Wi-Fi router or base station. If you're on a device with cellular service, make sure that cellular data is turned on
5. Try resetting (turn off and on) your wireless router

You could also try these steps:

1. Sign out of your ID (Settings > iTunes & App Store)
2. Reset your device's wireless settings (Settings > General > Reset > Reset Network Settings)
3. Reconfigure wireless settings on your device
4. without signing in, try and make purchase (It should have you sign in again at this point).

Or this:

1. Go to 'Settings'
2. Scroll down to 'Safari'
3. Scroll Down and tap on 'Clear Cookies and Data'
4. Tap on 'Clear Cookies and Data'

If you are still unable to make a purchase or connect, you might have to contact Apple as they may have blocked purchases.