How to fix the messaging on my iphone 4?

I was messing around on the messaging and I sent a really long message to a friend. After that the messaging app froze completely and then backed out. I tried to get on it a couple times and it would just try to load the messages and then fail again. I have restarted the phone twice and all other apps work but my messaging does not. I've been into it's setting but don't know what to do from there. I'm stuck. Please help if you have tutorial videos or even just advice!

Have you tried double tapping the home button and then holding down your messaging app and closing it from there? That will restart the app itself, if you just back out, the app stays open in the background.

Also instead of restarting the phone by holding down the lock button try this: Hold the lock button (Top right button) AND the Home Button (Circular button under the screen on the face of the phone) at the same time for approx. 10 seconds.

Hope this helps