My mailboxes containing all my mails has disappeared. How do I get them back

Hi,

If your mailbox accounts don't appear in settings, (Settings > Mail, Contacts, Calendars) you'll have to re-add them.

However, if they do appear, open Mail, tap Edit, and make sure every mailbox you want shown is checked.

I'm wondering about the cause. Have you updated iOS, made any changes in Accounts, iCloud, or even App and iTunes Stores?

Try resetting your Mail Account and system by following these steps. Please do not skip any steps. Go to Settings > Mail, Contacts, Calendars > locate your email provider and click on the account. Then on the next page Delete Account. Then do a forced restart. Hold down the Home and Wake/Sleep buttons at the same time for about 15-20 seconds until the Apple logo appears. Ignore the "Slide to power off" text if it comes up. You will not lose anything. Then go back to Settings > Mail… and add the account again.