ios Mail app shows Welcome to Mail screen even though I have already set up and have been using my account

I have an iPhone 4S currently running ios7.0.4. I have been using the built in Mail app since I bought my phone years ago and it has always worked fine. I have two accounts set up in the app. Recently (within the past month, maybe two) when I open the app, I am met with the Welcome/set-up screen that lists the different account types that you can set up (iCloud, Exchange, Google, etc.) even though I already have my accounts set up and they were working that morning. If I double-tap the home button and swipe up to close the app, and tap the app again to re-open it, it loads both accounts like normal.

This wouldn't really be too big of an issue because it has a quick fix, however because it doesn't recognize that a mail account is set up, it also does not alert me when I receive a new email. So I have to manually check my emails every hour to make sure I don't miss anything.

While the mail app is being weird and showing me the welcome screen, I can open up the mail settings and still see both accounts that I have, and notification settings are all as they should be.

Either I don't know how to phrase the questions properly to get hits on Google, or no one else has ever had this issue. Has anyone heard of this, or have any suggestions?

Thanks for the suggestions, tried both with no luck, then I actually went in and made sure every setting was set the way I expected them to be set.

Somehow, without my doing, the settings had been changed. I noticed this once before, my phone crashed and all of my custom ringtones/vibrations were unset for my contacts. Not lost, just unset.

In case someone reads this and is still wondering what settings you've missed, the particular settings that I had to fix were:

Notification Center > Mail > (Account) >
1. Alert Style [Alerts]
2. Show on Lock Screen [Yes]

I'm sure we all have those moments when the most obvious solution just can't be it and there's no point in checking because you're SURE there's NO WAY it could be it... oops :)

Screenshot tutorial

Wow I can't believe that was so easy!

This happened to me today as well. I put it in Airplane mode, restarted, then turned off Airplane and voila!