Iphone 5 video recording problem?

I have a 16gb iphone and only 3 apps downloaded (and still available space). Only 7 photos and no videos on my camera roll. Why are my vids not recording all of a sudden? I've had this phone for 6 weeks and it's been great, now videos won't record at all. I have filmed vids for over 10 minutes (and of course deleted them off my camera roll after i was done filming). Why is it not recording when there's still space on my phone?

Try rebooting & if that fails, restore the iPhone.