Need help with computer audio issue

I just have a basic 5-6 yo E-Machines computer connected to a Logitech woofer and speakers. In the past I would completely lose audio from time-to-time and just reboot and the audio would come back on. This time it's been two days and no audio. I've tried the typical troubleshooting - making sure the audio is not on mute, checking the connection from computer to speakers and checking power to the speakers. I can hear the speakers humming when turned fully up and they make that pop when I unplug the power cord to them. Any ideas what's wrong?

 

Yeah, Windows 7 - Not sure how to change "sound car settings"... Thanks

 

Thanks for the assistance, gents... After closer investigation it turned out the speaker cable from the computer was completely severed mid-way... I have no idea how that could have happened, but there is a lesson there somewhere I suspect.

BTW, turns out I still know how to splice a cable, minus a finger tip or two.

 

Plus, I learned a thing or two.