Hi LaAnDa,
Thanks for bringing your question to Apple Support Communities! It sounds like your son is unable to access his iCloud Settings because it is greyed out. iCloud is such a useful feature and I hope we can get it working again for him.
Be sure the iPhone has been restarted since this occurred: Restart your iPhone, iPad, or iPod touch.
Also, be sure his iPhone is completely updated: Update your iPhone, iPad, or iPod touch.
See if he is able to log into iCloud.com from a computer's browser.
If he is unable to log in, Contact Apple Support.
I hope he is able to access his account.