I have a DELL A525 and the is no sound coming out of the speakers or sub-woofer even with the blue light indicator on the speaker is ON and the sub-woofer vol. is high

Most likely the amplifier that drives it all is in the speakers, not the sub.

Try differnt speakers, if they do not produce sound, amp channels may be blown and then you need to take it to a shop.

Check your owners manual.You will probably have to activate the sub woofer outlet,using the remote.This outlet can usually be programmed to do more than one function.

green hole speaker plug hole

Select Start > (right click) My Computer > Manage
In the Management window select > Device Manager
Next to Sound, Video and Game Controllers click the + sign
A yellow triangle will signify a problem so if one is present, right-click that device and select Properties
You can then choose to update the driver
For more details check Dell Xps 420 Manual.
Dell Xps 420 Manual

sounds like they are picking up interference. make sure they are grounded well.

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Buy a new one

ADUJST THE SOUND WITH SPEAKER ICON ON THE START BUTTON MENU BAR DOWN

Here's the fix: power off the sub-woofer and wait for 60 secs before powering it on again. My rear receiver works every time now.  I guess the sub-woofer isn't just a dumb speaker; it has some kind of smarts in it too.
Prior to this, I had only tried cycling power to the DVD player itself.  I also re-seated the two, fat cables connected to the junction box. One of them had worked itself slightly loose and the result was completely absent speaker channels.