I am unable to get the forward and backward keys, volume keys working, nor the play pause keys. I am using lubuntu 14.04 LTS
Try another music player (for example, audacious, banshee,etc) (sudo apt-get install audaciuos or sudo apt-get install banshee)
Try another desktop environment (gnome, xfce) (sudo apt-get install gnome or sudo apt-get install xfce) Xfce would be a better option if your machine is rather weak (less than 4 gb RAM)
In XFCE go to Settings Manager > Keyboard Preferences > Shortcuts.
Also your keyboard button may not not be supported yet. Then you will have to wait for updates.