I've got a friend who has got a problem with his webcam - when he tries to turn it on it's saying device cannot be recognised

Send this to him and see if it helps.
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Try disconnecting the Camera from the USB port and reinstall the CD or Downloaded software program. When the program asks you to connect the camera to the USB port, do so and it should work.
Then to use it on the Web do this.
Web Camera’s have to be setup on the program they are to be used with. Just installing the camera on your computer does not set it up to broadcast on messengers or Skype.
Each program has Options that have to be setup in order for the Audio and Video to function properly.
A. Skype Setup:
After downloading and installing Skype (http://www.skype.com/intl/en-gb/download/skype/windows/beta/downloading/ ) set it up as follows:

1. Go to Tools, then Options, and click on Audio Settings and set the Microphone and Speakers to the computer Audio Card.
2. Then click on the Video Settings.
3. The camera if Installed Properly will come up and show a video picture.
4. Then, on the bottom of the page click on Save.

1. Go to Messenger at the top left and click on it.
2. Next go down to Preferences and click on it.
3. Next Calling and Devices on the right and set the Microphone and Speakers to the computer Audio Card.
4. Next go to the Test Audio section and (in blue writing) click on “Open the call setup assistant” and follow the instructions on the left window.

1. After you start Windows Live Messenger, expand the view by clicking on the square on top left next to the red X.
2. Then on the Windows Live messenger window on the right side, click on “ “Show Menus.” And then click on “Show the Menu Bar”.
3. Next go to the Menu Bar on right side, click on “ “Action.”
4. Go to “TOOLS” and click “Audio and Video Setting” and follow the instructions.