Mac can't find camera problem solved

FaceTime shows "no camera detected" and so on, the camera may be working properly after reboot, the camera is unstable

Restore normal after resetting NVRAM, it is said that this method can also be used when the machine card.

https://support.apple.com/zh-cn/HT204063

How to reset NVRAM on a Mac

Learn about the NVRAM of your computer and when and how to reset NVRAM.

What is NVRAM?

NVRAM is a small amount of computer memory, the full name of "Nonvolatile Random access Memory", used to store certain settings in a location where OS X can be accessed quickly. The settings stored in NVRAM depend on the type of Mac you are using and the type of device the MAC is connected to.

The information stored in the NVRAM includes:

• Speaker volume
• Screen resolution
• Startup Disk Selection
• Recent kernel crash information (if any)

If you are having problems with these features, you may need to reset the NVRAM on your computer. For example, if your Mac is not started from the startup disk specified in Startup disk preferences, or if a question mark icon appears briefly when your Mac starts up.

Reset NVRAM

1. Turn off your Mac.
2. Find 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 key immediately after you hear the startup sound.
5. Press and hold the keys until the computer restarts, and you will hear the startup sound again.
6. Release the keys.

After you reset NVRAM, you may need to reconfigure the speaker volume, screen resolution, Startup Disk selection, and time zone information settings.

If you still have problems with these features on your MAC desktop computer (such as IMac, Mac Mini, or Mac Pro), you may need to replace the motherboard battery. The motherboard battery on your desktop computer is used to help save the NVRAM settings when you unplug your MAC's power plug. You can bring your MAC to the Apple retail store or to an Apple authorized service provider to replace the battery on your motherboard.

Learn More

On older MAC computers, similar information is stored in parameter RAM (PRAM). Resetting the NVRAM with the same key combination on an Intel-based Mac is equivalent to resetting the PRAM.

Power-related settings are controlled by the System Management Controller (SMC) on your Mac. If you're experiencing problems with powering up your computer, sleeping, waking up, charging your Mac laptop battery, or other power-related symptoms, you might need to reset the SMC instead.

Mac can't find camera problem solved