accidentally Removed app

Hi
I just bought a new GL S3 foon for my son en yesterday he has accidentally remove one of the system apps. He was not rooted the only thing he has done is removing the check mark beside the app in the application list short cuts ( i think) now when he goes to the apps he can still see that app there but when he try to start it he get this: Application is not installed.

Can someone tell me how to get this app back?
The name of the app is galery for watching and editing Photos.

Thanks

 

Hi M,

Thanks for the replay,

I will try your suggestion as the last resorts , but i want to konw how to restore this app or any other system/apps in future
I was not rooted so how could this app be removed? and it should be a way to reinstall the system apps (except reset to default factory) am i right?
Thans
Shahin

 

Hi Hery,

Thanks for your replay,
I didi check the location that you mentioned but i cant see my app there.
Can i use the root explorer to check for this removed app?

Thanks

 

Hi Hery,
Thans for your update,
You are right the removed app was in the end of the list! Thnk you for your help on this issue.

Thanks