Why i can’t download free apps ??Can i use my itunes card for billing method?

Free apps requiring a payment method is not an uncommon observation . Some possible reasons are outlined in the links below such as outstanding balance, an issue with a payment method you have currently entered, or ongoing subscriptions. You can try to set up your account without a payment method but you may find there is no option other than to enter a valid payment method to satisfy Apple's requirement. If the item is free you will not be charged. You can also later remove the payment method and see if it only needs to be there temporarily.

If you can’t download or update apps on your iPhone or iPad - https://support.apple.com/HT207165

- "You might need to have a payment method on file, even if the app that you want to download is free." My interpretation of this is if you have something else on your account that requires a payment method, such as a subscription, and your payment method is not working then Apple won't let you download even free things until you fix the payment method. This is explained in this document, 'If your payment method is declined in the App Store or iTunes Store' - https://support.apple.com/HT203005

Create or use your Apple ID without a payment method - https://support.apple.com/HT204034

- "You can remove payment methods from your existing Apple ID after you sign in to the App Store, iTunes Store, or Apple Books. You won't be asked for a payment method again until you make a purchase." To me it isn't clear if a free item also counts as a true purchase, but if it does then you need a card to get your item. Note: I download only free items and have never had to enter a card.

If you can't remove your last payment method or use no payment method with your Apple ID - https://support.apple.com/HT203905

- " if you're using an existing Apple ID with the App Store for the first time, you must provide payment information."

If you still have problems 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." - https://support.apple.com/HT201232

And no, you can't use your iTunes card. I presume you mean a gift card. In order to use that you have to redeem it which then puts balance in your Apple ID, but it is not a substitute for a credit/debit card.

Redeem your App Store & iTunes Gift Card; click here --> https://support.apple.com/HT201209