How to turn camera click on?

Do you possibly have the mute switch engaged? It's the little slider above the volume buttons.

There are many countries where putting camera shutters to silent is illegal

Hence if you have bought an iPhone from any of these countries, you cannot put it off.

SravanKrA wrote:

Hence if you have bought an iPhone from any of these countries, you cannot put it off.

The OP wants to turn the click ON not OFF.