[santod]

Often this is the result of having done a restore of a backup at some point. Or viewing a text when a new one comes in containing a picture.

Here's one possible way to fix this, although it doesn't always.

Simply send yourself a picture message (MMS). After the message has been sent. While you’re waiting for it to come back go into your text messages and read the first one. Stay in the message screen and wait for the MMS to be delivered. Once it’s been delivered and you see the “New Message” indicator at the top of the screen, scroll left once. This should now display the MMS that you just sent yourself. Now go back to the Today screen. Voila! No more “phantom” unread message!