no sound in playback (SOLVED)

I have been using Audacity for some time now on Windows Vista with headphones. Suddenly I got no more sound on playback. The VU-meter shows sound output. I have checked the playback volume, fiddled with other settings in Audacity, checked Sound in Windows settings and in other sound editors (the connection and head set are fine), updated from 2.0.0 to 2.0.3, and tried to find other solutions in the FAQs.
Frankly, I am at a loss now. Can you offer me advice, what the problem might be?

Which version of Windows?
What sort of sound card?
Where are your headphones plugged in?
What settings o you have in the Device Toolbar?
Do you have a USB audio device plugged in?
Do other audio applications work?

Check your windows audio settings (outside of Audacity) and make sure headphones are selected as the default playback device. Other things should work through headphones (watching Youtube for example), and then try in Audacity. Audacity typically matches the input/outputs of the PC so if the PC side of things works fine, Audacity SHOULD. But like all things, sometimes a setting goes boink.

Damien

Which version of Windows?
What sort of sound card?
Where are your headphones plugged in?
What settings o you have in the Device Toolbar?
Do you have a USB audio device plugged in?
Do other audio applications work?

Windows Vista, as I said in the post
I have sound on my head phones, just no sound with Audacity since two days.
Everything is like two days ago, when Audacity worked all right. I see no point in checking it all out. I cannot imagine any hardware malfunction that would cause Audacity to stop playing audio, with no effect on other audio. I mentioned this in my first post: I checked sound editors. For the record, I checked Media player and Roxio: audio is fine.
I tried playing Audacity with my mp3-player both plugged in and disconnected.
And I’ll menton again: I updated Audacity to no avail.
I really think the problem is in a setting within Audacity.

possibly in the Device Toolbar

Yes! In Modify > Preferences Output was changed from Windows output into Digital output.
The cause of this change is a mystery, but my gratitude is real!