Q: My IPhone 6's app store doesn't word because it does't recognize my mastercard number and i dont know what to do

Hey Shereef mohssen,

I understand that you're not able to update your billing information for use with the iTunes and App Store on your iPhone. The information outlined below provides next steps for getting your billing information set up in the App Store.

If you need help changing your payment information, credit card details, or billing information, contactiTunes Store support. Or you might find the answer to your question below:

• If you change your payment method, make sure your account information matches the credit card information on file with your financial institution.
• If your previous payment wasn't accepted, you might need to change your payment information.

Change or remove your Apple ID payment information
https://support.apple.com/en-us/HT201266

Cheers!