Hi, GPad55! Welcome to iPF!
Try to force close the Mail app:
iOS 6: double tap Home button to reveal the multitask bar, then tap and hold an app icon there until they start to wiggle, and delete the Mail app icon there.
iOS 7: also double tap Home button, but swipe the thumbnails above the app icons (pictures) towards the top of the screen.
Open the Mail app again afterwards and try to access the emails.
Hope that helps.