Sounds like a device driver error. Try checking device manager and seeing if there are any problems there. Also check Dell's website for the latest drivers for your Model and Install them.
I have no sound from my dell laptop(running XP).
No sound from the internal speakers
No sound ussing head phones.
I do have a blutooth sound and voice device that works fine.
Any suggestions i think since blue tooth device works there might be a hardware problem.
i trying this route before taking it to repair shop
Any suggestions would be grealty appreciated.

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