My iPhone 6's volume is stuck on mute, but the silent switch is still working.

My iPhone 6's volume is stuck on mute, but the silent switch is working and calls and alerts still come through with noise. However anything that requires volume e.g. music, videos, etc. cannot be heard. Even with headphones in the noise will go straight down to mute instantly. Also the volume mute symbol is permantely on my screen and is not fading away.