Sub woofer working speakers not

Hello,
i have a dell hybrid with Logitech sub woofer and two speakers.
Cannot get speakers to work.
All sound is coming from Sub woofer.
If i put headphones inot the HYBRID Box, it can hear perfectly well.
Take headphone jack out, no sound. Well muted stuff coming from WOOFER. Did a test on the PC and the speakers work when you are asked to test them.The realtek sysyem where they take you thru the speakers and put mouse on to test.

very, very frustrating, to someone who knows nothing about computers.
I am sure it is easily solved too.

Any suggestins? Anyone?