To start with open the 'Sound' application, make sure the output volume is set to 100% and the connector is set to Speaker. If you have more than one "device for sound output" then try an alternative. You could also look under the Applications tab to see that the apps using sound are recognised (you have to be using a sound app to see it there though, so play some music or something).
Fujitsu Lifebook AH532. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Lubuntu 13.10,Ubuntu12.10 (Unity), Mint16 (Cinnamon), Manjaro (Xfce).