iCloud mailbox disappeared from Mail app on iPhone 6
I have iPhone 6, updated with the very latest iOS. I have several email accounts, one of which is my personal iCloud email account.
My iCloud email mailbox (the entire mailbox and all folders) has completely disappeared from the Mail app. My other email accounts still appear.
However, my iCloud account still appears in Settings/Mail, etc., and when I try to recreate my iCloud email account, it tells me the email account already exists.
I also have an iPad, and all of my email mailboxes still appear in the Mail app on my iPad, which is working perfectly. It seems as though my missing email mailbox is related only to my iPhone 6.
How can I retrieve my email mailbox in the Mail app on my iPhone 6?