My sound effects aren't working, how do I get them to work again?

On my iPad my sounds effects aren't working and it's on loud. I've been into music but it won't let me change the volume. It's just dark grey and won't let me touch it. Also the volume control on the side when I put it onto loud the sound effect pops up in the grey box but doesn't let me change the volume there either... I've also been through the settings and cannot find anything or anywhere where it will let me change the volume manually or invade it had been turned off by accident. I can't listen to music or hear when it goes off!!!

PLEASE HELP!