AssistiveTouch is one of the accessibility features built into iOS that makes the devices easier to use for people who have difficulty performing certain gestures. The feature can also be used as an alternative to using your Home button. If your Home button is not working, you can still navigate your iPad, iPhone or iPod touch using AssistiveTouch. In addition to providing a virtual Home button, AssistiveTouch can also simulated the Sleep / Wake and volume buttons on you iOS devices.
Once AssistiveTouch is on, you should see this icon .
You can hold down on the icon and move it along the sides or bottom of screen. Tapping on the icon reveals the virtual Home button. The virtual Home button recognizes double taps and when you hold down on the button, just like the actual Home button.
The functions of the Sleep / Wake button can be simulated using AssistiveTouch by tapping on Device then LockScreen. Tapping LockScreen will immediately put the device in the sleep mode. You can power off your device by holding down on LockScreen until the red “Slide to Power Off” appears, then use the slider.
AssistiveTouch allows you to adjust the volume, rotate the screen and simulate shaking the device with a tap. Although, Apple may have not intended AssistiveTouch as an alternative for defective buttons, it will allow users to make do until the device can be repaired or replaced.
For more information about AssistiveTouch, check out this Apple support document.