iPhone 4 volume not working. Help please?

The volume on my iPhone 4 is not working. When I press the volume buttons on the side either nothing happens or the volume/sound icon comes up but without any white squares that identify the volume underneath it. When I go to music there is no volume bar, it is just blank space. Also when I double-click the home button there is normally a volume bar when you slide over to the music menu but there is not. I have tried restarting my phone, restoring it and turning off and on again the "change with buttons" option on Settings>Sounds. If anyone knows how to fix it that would be great. Thanks!