I can't use camera app.
Do you have restrictions on?
Settings > General > Restrictions: should be OFF > Camera: ON
No restriction is off.
Reset: Hold down the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears. Note: You will not lose any data
It's not ok.
Give us more info, maybe someone here can help you.
You can't use the camera app? That tells us literally nothing about the issue. Please try and explain a bit better what is happening.
When I use it ,shutter doesn't open.
Was it hacked/jailbroken?
No,it is not jailbroken.
You got 2 more options:
1. Restore from backup using iTunes
2. Restore as new without the backup, afterwards manually sync content back.
Retrieving data ...