My emails are hidden. How do I unhide them

I know you solved your issue, Peter, but for the benefit of others with a similar problem I'll describe my situation. I would have emails on my iPhone 6 disappear, whether read or unread, if they were at least a few days old. This was a "Mail Days to Sync" setting issue. If it's set to let's say 2 weeks, emails older than 2 weeks will be hidden. You'll find them if you search for them, but they won't show up among emails listed in the inbox. Here is how I changed that setting so as to unhide emails and to keep other emails from being hidden:

Settings -> Mail, Contacts, Calendars -> select your email account under "ACCOUNTS" -> Mail Days to Sync -> change the amount of time

The farther out a timeframe you choose, the farther out emails will remain unhidden.

What do you mean hidden? Please tell us about the steps you take, the result you get and what you'd expect to happen.

Sounds to me like your mail database got corrupted on the phone.

I would suggest disabling the account (Settings -> Mail, Contacts, Calendar -> select your account at the top and then disable the switch next to mail), then switching to the Mail app (which should not show any emails now), and then re-enable your account (by going back into settings and setting the switch next to Mail back to on). Then go back to the Mail.app and see if that helps.

Strange... yes, deleting the account would be the next step I'd try. Usually this does not really cause any problems, the iPhone should just download your messages and everything should be fine.

May I ask where you have your account? Does the provider have a web-based login?