I have the Boston Acoustics BA745 Computer Speaker System. I cannot get the Sub-Wolfer to work. Everything is plugged in but when I turn the volume up on the left speaker module, nothing happens. Is there a setting I am overlooking on my HP Computer?

This could be because the speakers arn't getting a stereo signal, but first, double double TRIPLE check the wires are connected correctly. Iknow it sounds patronising but I don,t know if you are 8 or 80 years old and it's often best to go for the most obvious solution. afer making sure all connections are correct, have a look at the cable to the subwoofer - is there any damage to the cable or does the cable look like it may have been pulled - out from the sub or it's connection at the other end of the cable? Having eliminated the possibility of cable damage (it may be worth cheacking the cable to the pc) check various settings on your pc - are you getting sound from your other two speakers? if you are only getting sound from one of the left/right speakers and you're sure there's no physical failure with the speakers, then it's time to check your software. go to the little speaker ikon at the bottom right corner and right click. Select "Playback devices" select "speakers" and click "test" did you hear sound coming from the left speaker then the right? if yes then you definately have a problem with the sub. if no, click "properties" then "levels" and check the balance is set to the middle. If it is, then you should, again, suspect the speakers. Finally check the balance on your media player, if you use windows media player, go to "options" click "enhancements" then look for the balance control and make sure it's in the middle.
Finally, I would like to point-out that this particular speaker system is not known for having a loud subwoofer, put your ear against the hole in it and double check for anything happning inside (a crackling noise would indicate a danaged voice-coil.

Hope this helps.