Why is my sound not working?

A while ago, the sound completely stopped working on my laptop - I had speakers plugged in at the time and the sound just died completely. It does register that there are sound input devices and changes from internal speakers to headphones if I plug something in the port, but it won't make any sound. The internal mic doesn't register any noise, and the computer doesn't even chime when I turn it on. Has the sound card gone bust, or is it possibly disconnected somehow? I'm pretty useless at computers so if you have some suggestions, please make it as idiot proof as possible! Thanks!