App gifting

Contact Apple:

Click here --> https://support.apple.com/choose-country-region/media-services Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world." Click here --> https://support.apple.com/HT201232

Did you check your junk mail?

Ask your friend to resend it, making sure he/she has the correct address:

Resend iTunes Gifts - https://support.apple.com/HT201591