Compac laptop, no sound

first of all check whether u have installed the sound card drivers correctly or not .If u have installed them correctly when u connect the external speakers to your laptop then a pop-up will come and ask u for the type of input you are giving . Just select the option as Line - out or headphone and increase the volume of these in the Sound and Audio Devices in the control panel.

compaq laptop required high defenition audio bus which you can download from support site
of hp. let me know what is the modle no of your laptop.