no sound after ios 7 update

I've just updated my iPhone 4 from iOS 6.0.1 to 7.0.4, and I have no sound at all from the speaker. If I plug headphones in music and general audio plays fine but when I remove them I get absolutely nothing. I've tried the navigation sounds from iOS, music, videos, ringtones, speakerphone in a call, and still absolutely nothing. Can anyone offer any help?

Thanks