Using Outlook for iOS for personal email and calendar management
HiSarah, your emails might still be there but hidden! This usually means the Mail app's got the wrong settings or isn't syncing right.
First, see if your account's set to Fetch or Push in Settings > Mail > Accounts > [Your Account] > Fetch New Data. Also, check if you've got any filters on by tapping Filter at the bottom of the Mail app. If that doesn't work, try deleting and adding your email account again.
Is this happening with just one account or all of them? And are you using iCloud, Exchange, or something else?
Regards,
Rez