how to restore my iphone when my phone cant turn on

my iphone 4 want to upgrade to ios 7,after few hour later my iphone screen turn it into plug in itunes logo.then when i plug in to the computer,it show i needed to restore my iphone.but the problem is my phone cant open to the main page,it just stuck in the plug in itunes logo.i have try restart my iphone oso,but its still not working ,it come back to the same page.so my questios is how can i restore my iphone?