Most of the times, iPhone users do not restart or soft-reset their device quite often. That’s the way Steve Jobs and Apple built it. The device does not have a switch that completely switches off the device (even if you slide to shut it down). Now, if you go to make an appointment for the genius bar via the Apple Online Store, you will be asked to firstly try a simple step.
You are required to press and hold the sleep and home button together for more than ten seconds till the Apple logo appears on the screen. The device will then be restarted and as Apple believes, this would solve the majority of the issues and would not require a genius bar appointment.
If this still does not resolve your issue, Apple will be glad to book an appointment for you with one of the geniuses from the genius bar.