I also had this problem with a webcam someone gave to me yesterday. It is USB device, a Genius iLook 320. Naturally there are windows and mac drivers, but nothing official about using it with Ubuntu.
Therefore, RTFM for guvcview. Open a terminal, and type
man guvcview
It says, among other things:
"-d, --device=VIDEO_DEVICE Video Device [default: /dev/video0]"
Make sure your webcam is attached. Then go to the terminal and enter the command:
ls /dev | grep -i video
The reply is:
video1
Aha! The default device that guvcview uses, video0, DOES NOT EXIST!
Therefore, you must make guvcview use the device that exists, because that's where your webcam is.
at the terminal:
guvcview --device=video1 &
and it should work. If you run guvcview from the menu, edit the menu item, adding "--device=video1" The "&" is for running from the terminal. There are other command line options given in the man page, and I have not tried to figure out what they do yet.
When you run guvcview from the terminal, you will see a lot of messages about "ALSA lib" which is for sound (which my camera does not have), and other messages such as:
"{ pixelformat = 'RGB3', description = 'RGB3' }"
These messages might help you configure video quality.
The first time you run it, it will create a configuration file in your home directory: ~/.guvcviewrc-video1
You can edit this file as desired. The default picture quality of my device leaves a lot to be desired. YMMV.