Hi harsha676,
Thank you for using the Apple Support Communities. Keeping your iCloud storage billing up-to-date is certainly important. As we understand it, you've added funds to your Apple ID balance but it doesn't appear to have deducted, and you're unable to download apps.
To verify, what exactly happens when you try downloading an app? Does it mention your account being disabled? If so, check out this link: If a message says 'Your account has been disabled in the App Store and iTunes'
Otherwise, we recommend using this link to contact Apple directly to look into billing for iCloud storage: Get Support
Kind regards.