app store

See -> If you can't connect to the App Store, iTunes Store, or other Apple services

If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support

-> If you tried all of the above steps and you still can’t connect, contact Apple Support.

See the following Apple articles: 

Redownload apps and games from Apple

Redownload apps and games from Apple - Apple Support

Redownload music in the iTunes Store app on your iPhone, iPad, or iPod touch

Redownload music - Apple Support

Click here for more support and assistance.