The Home button is commonly the first button on an iPhone to stop working correctly due to how often it is used. If you notice that your Home button on your iPhone has stopped working, there are several things you can do to fix it.
The first thing to do if your Home Button stops working is to calibrate it by opening any app and then hold the Sleep/Wake button until your iPhone Power Off screen appears. At this point, continue to hold the Sleep/Wake button for about ten seconds longer. This should make your Home button start to work again. So, go ahead and try it again to see if this has happened.
If calibrating the Home Button on your iPhone didn’t work to make it operational again, then it might mean that you need to realign the actual 30-pin connector and you can do this by plugging your iPhone into its charger and as you are doing this, lightly push the charger against the backside of the home button, then press down on the Home button.
If the two previous steps didn’t work, then it could be that the home button is being obstructed from working properly from dirt. You can clean is by using 99.9% isopropyl alcohol. This is the only type of cleaning agent you should use, including rubbing alcohol due to the water content I them that can ruin your iPhone.
When you are sure you have 99.9% isopropyl alcohol, add just a couple of drops in and around the Home button and lightly tap it so the alcohol will settle underneath. Set your iPhone aside for about ten minutes, then check to see if the Home Button is working. If not, you may have to give up, but you can setup an onscreen Home button to replace it.
To setup an onscreen Home button for your iPhone, make sure that the onscreen accessibility button is enabled. You can do this by going to Setting, then General and scrolling until you see the Accessibility tab that is located toward the bottom of the screen. Then select the AssistiveTouch option and turn it on. This will put a small circle on your screen that will allow you to select the “Home” option on your screen instead of using the regular Home button.
Source Mashable