volume buttons not working on iPhone 4s

Hi there, my volume buttons don't work and some weird issue with the speaker on my iPhone 4s.

When I go into Settings-Sounds and click on 'Ringer and Alerts' the volume buttons work and I can hear the sound through the main speaker but when I go into the main home screen they don't work. I tried to put in silent mode and than into normal mode but still don't work.

When the headphones are connected they work fine but as soon as I remove the headphones they stop working.

Also, when I try to play videos the sound doesn't work probably becuase the volume is turned to minmal which I can't control. Through headphones it works fine but as soon as there out no sound comes out.

I've openend the phone and removed the buttons, gave them a good clean with alcohol along with the circuit board but after installation the buttons still don't work.

Is there something I can try to do to fix this or do I need new Headphone Audio Jack Volume Mute Silent Switch Button Cable?