Camera in not found after Yosemite upgrade.

Question

2012 Macbook Pro
Things we have already tried. (Several times)
First - find out if the computer recognizes the camera. Check System Profiler (in the Utilities folder, inside the Applications folder). Under the USB header, check to see if the iSight camera is detected.
Second - SMC reset for your machine.
1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.
Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.
Third - Resetting NVRAM
1. Shut down your Mac. Unplug the Power Supply and wait 15 seconds then plug it back in.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
3. Turn on your Mac.
4. Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
5. Hold these keys until the computer restarts and you hear the startup sound for a second time.
6. Release the keys.
Forth - Quit all open apps that may try to use the camera. Go to Application/Utilities/Activity Monitor and sort by process name. Find VDCAssistant. Double-Click on it to open the window about it and click on quit to stop the process.
Or kill it through the Terminal App.
  Quit all open apps that may try to use the FaceTime camera.
  Open Terminal, found in the /Applications/Utilities directory in OS X.
  Enter the following command string exactly, then hit return:
sudo killall VDCAssistant
  Enter the administrator password when requested, this is required to execute a command with superuser privileges as prefixed by sudo.
  Relaunch the app that was attempting to use the camera.
Fifth – Repair Disk Permissions . Go to Application/Utilities/Disk Utility, select your drive and click repair Disk Permissions.
Sixth - Run the Apple Hardware Test and see if you get any errors.
You need to connect to AC Power when running the Apple Hardware Test on a Mac notebook.
Set up your computer on a hard, flat, stable work surface that allows for adequate air circulation under and around the computer (such as a desk, table, or counter).
Shut down your computer. Then, press the power button to turn it back on.
Press and hold the D key before the gray startup screen appears.
It takes a minute or so for AHT to start up and inspect your hardware configuration. While this is taking place, an icon appears on the screen:
When the process is complete, select your language and click the right arrow. If you aren't using a mouse, you can use the up and down arrows to select a language and then press the Return key.
The AHT console appears. You can choose which sort of test or tests to perform:
To perform all of the basic tests, click the Test button or press the "T" key or the Return key.
To perform a more thorough diagnostic test, select the "Perform extended testing" checkbox under the Test button before you click the Test button. Your test results will appear in the window in the bottom-right of the console.
To exit AHT, click Restart or Shut Down at the bottom of the window.
Any other suggestions? Thanks!

Answer 1

Reinstalling OS X Without Erasing the Drive
Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Reinstalling OS X Without Erasing the Drive
Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the main menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility and press the Continue button. After Disk Utility loads select the Macintosh HD entry from the the left side list.  Click on the First Aid tab, then click on the Repair Disk button. If Disk Utility reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit Disk Utility and return to the main menu.
Reinstall OS X: Select Reinstall OS X and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.
Also see:
Reinstall OS X Without Erasing the Drive
Choose the version you have installed now:
OS X Yosemite- Reinstall OS X
     Note: You will need an active Internet connection. I suggest using Ethernet
                 if possible because it is three times faster than wireless.