In order to independently fix the webcamera, install the root cause of the fault. First check your computer for viruses, and then proceed to reinstall the device driver.
Open control panel, go to "add or remove programs" and then uninstall the driver from the list. If you have the skills to work with the registry of the operating system, run the cleaning from the records of the remote software.
Download an updated driver for your model webcam, install it on your computer following the preliminary restart of the operating system. If the camera still will not operate, check integrity of wire connections and try changing the port.
If it's built into your portable computer, remove the monitor case and check the wiring. Also note whether you have a working microphone, if the configuration of your model provides one controller for their connection. Malfunction most likely in this case can be attributed to internal damage.
If you find any damage of a mechanical nature in your webcam, contact specialized service centers, as disassembly of the cameras should never be done at home without special tools.
You can disassemble yourself only the body of the device without affecting the lens, which in total will not give any results concerning the malfunction.
Even if you will find somewhere the service manual to disassemble and repair your camera, don't do this at home, because, most likely, you just completely ruin the device. If you still have the warranty on the device, replace it with a new one by contacting the manufacturer or retailer.
Periodically check the integrity of the wires connecting the devices.