Incase any one of you have faulty or non working buttons on iphone, i have got a cool solution to share. This solution is a feature in all iphone (4, 4s, 5, 5s,6) but hardly anyone knows it or uses it. The faulty buttons and non working button is a common complain you woul hear or experience specially with the old iphones or the ones which are not kept well.
The feature is called the "Assistive touch" which gives a dark spot on the screen ( the spot turns light invisible) and represents the home button of iphone. Not only it acts as a home button it gives access to use and function the other buttons on iphone which are volume ( both up and down) and the power button on the top.
The assistive touch can be activated by going into settings>general>accessibility> (keep going down) assistive touch> On.