Try using Ekiga see if the cam works/detected. You may have to work with the settings > Open Ekiga > Edit > Preferences > Video > Video Devices > try changing some of the settings.( Video Plugin if it shows V4L change to V4L2)
To test your webcam you can do this:
There are 6 icons on the left side of the main Ekiga window. Push the 4th button from the top (a grey round webcam). If eveything is ok, you'll see the output of the webcam. If not, you'll see the Ekiga logo bouncing slowly.
If the Ekiga didn't work post results of the command > lsusb
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