No sound from speakers, only through headphones

I am using Dell Inspiron 6400 laptop running Windows XP Media Center Edition with SP3. Last 2-3 days ago, I started having issues with the sound and it only works through headphones, whether from a website or a CD/DVD or a file on the pc. I tried restarting but that didnt help either. Dell Diagnostics test is working fine and I can hear sound from the speakers while it was running. The Device Manager shows no issues. Is there any other solution? Thanks.

When you are double clicking on the volume button, then can you pick options and then go to properties and what does it shows in the Mixer Device window over there? You need to ensure the Playback is selected for Adjust Volume for.

Do you by any chance using it as a desktop and have external speakers, they normally require power I think.

Since it is an external Powered Speakers, then do the following:

1. First of all check there is power to the speakers.
2. After that you have to check the speakers are turned on.
3. Now you can try to check a volume control on the speakers is not at minimum.
4. After that check a mute control on the speakers is not active.
5. Now try to plug the headphones into the same jack as the speakers to test the output.