a) The sound on the app is not working. What can I do?
1-Check the side switch is set to Mute, check to make sure it’s not muted (in vibrate)
2. Check the Volume buttons
3. Double-click the Home button; swipe the Task Bar to the right. Check the Mute and Volume settings.
b) How to redeem a promo code?
Step 1: Launch iTunes and go to the iTunes Store.
Step 2: Make sure you are on the iTunes Store homepage, and look to the right, in the sidebar, you should see the following image.
Step 3: Click on “Redeem”, which should take you to this page:
Step 4: Enter the promo code in the text box, then hit “Redeem”. The app will start downloading to your library of apps.
From the App Store:
Step 1: From your iPhone, go to the App Store app.
Step 2: Navigate to the “Featured” section.
Step 3: Scroll all the way down, and tap the “Redeem” option. You should now see this screen:
Step 4: Enter the promo code in the text box, then hit “Redeem”. The app will download to your iPhone as if you had purchased it.