i have lenovo laptop with window 8.1 when i am clicking on camera it's showing that "another app is using camera app first close that app & try again".And any app is not opened.What i do.
If it's not a driver issue: You can also try, to deactivate the camera in device manager. After it, reactivate it again. If there really was an app using it, you've stolen it from that app, and it's possible now to get the handle on the camera.
Later you can try to use process manager to find the nasty app.
You can try to restart your computer and if that does not help you can uninstall the lenovo drivers and just use the windows 8.1 ones because it could be a conflict between the two drivers
Process manager is your best bet. Look for anything that might possibly use your camera. Lenovo laptops like that often come with a lot of bloatware that might use the camera. Also try restarting your computer, and disabling the camera in the device manager.