Didn't you get a message in the computer that it itunes has detected an iphone in recovery mode?
Let's first download and install the latest version of itunes to the computer. You can download the latest itunes by going to
Once you download it, install it.
Then try the same procedure again. Let me know if that works.
Open itunes in the computer and connect the iphone to the computer. Now, on the iphone, press and hold the power button and the home button together until you see an apple logo. The very moment you see the apple, let go off the power button but keep on holding the home button for another 10-15 sec. Your computer should now give a message that it has detected an iphone in recovery mode and needs to be restored. Restore the iphone now.