My iphone 4s won't let me take a pic?

When I go to take a picture it goes straight back to the home screen and instgram won't let me take or post pics help

Internal might be full

Your photo memory is probably full and if it isn't then its probably just a problem with your phone. Try to shut off your phone and if that doesn't work then you might need to reset your phone. Don't worry your pictures won't be lost or anything but the Wi-Fi settings, your passcode lock and you home screen and lock screen picture, you might have to put it again. To reset it go to settings<general<scroll all the way to the bottom, and hit reset. Your contacts and anything won't be erased! Just the basic things will need to be put again. If your too afraid to do this or if this doesn't work then maybe you might need to go to your phone company.