uninstall camera and reinstall on iPhone I bought a new Iphone 5. back camera never worked since then. no issues with front camera. camera application also hangs now and then. I want to un install the camera app and re install it. is this possible? 

I bought the phone in America and currently using it in India. not sure if I can service it in my local Istore in India.
You can't uninstall the Camera app as it is a built-in app. Instead, you will need to reinstall iOS by connecting the phone to iTunes over USB and clicking Restore in iTunes.

This also will allow you to back up the device and save your apps and content.

Lastly, Apple's warranty is worldwide and you can initiate service in the US online and via phone at http://support.apple.com and if you need a repair, they will give you options even if you are in India if it turns out to be hardware.