This is unfortunately a long list of things to check but you have provided too little information for us to propose a specific solution. Describing what happens when you try, and the exact wording of any error messages, would greatly aid us in helping you. In the meantime review these suggestions and documents if you think they apply:
Read this document if you can’t download or update apps on your iPhone or iPad --> If you can’t download or update apps on your iPhone or iPad - Apple Support
If the first 5 don't help, use the 6th.
If you see a message that says "Your account has been disabled in the App Store and iTunes", follow the directions in this document --> If a message says 'Your account has been disabled in the App Store and iTunes' - Apple Support
If a feature on your device is not working, it may have been disabled. See how to 'Use Screen Time on an iPhone, iPad, or iPod touch' by clicking here --> Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support Go to: Content & Privacy Restrictions > iTunes & App Store Purchases and allow adding and deleting apps.
Learn what to do if you can't redownload an item or if you don't see the item in your purchases.
If there's an issue when you redownload apps, movies, or other content from Apple - Apple Support
- Items bought with another Apple ID, and about Family Sharing.
- Incompatible apps.
- Hidden items.
Other considerations:
Do you have the same problem when using a different Wi-Fi network?
Does restarting your device make any change?
Can you download apps normally on another device?
Did you try restarting your device?
Resolve issues between iTunes and third-party security software - Resolve issues between iCloud for Windows or iTunes and third-party security software - Apple Support - You can’t connect to iTunes Store to buy or download content.
Have you entered a payment method? This document explains how to add a payment method to your Apple ID' on an Apple mobile device, a Mac, or a PC; click here --> Add a payment method to your Apple ID - Apple Support
Check Apple's system status to see if a server is having problems --> Apple - Support - System Status
If you can't connect or sign in to iCloud, see if this document has a solution --> If you can't connect or sign in to iCloud - Apple Support
If you can't connect to the App Store, iTunes Store, or Apple Books, read this support article --> If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support
- If none of the suggestions work, try the last one: "If you’ve tried all of the above steps and you still can’t connect, contact Apple Support."
Click here --> Choose your country or region - Official Apple Support 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
