How do you unfreeze your iphone when you were updating it and then it froze?

I took the iphone off the charger when it was updating from the computer. On the screen it has the apple and a loading bar but the loading bar isn't loading. I took it off the charger because it said on the computer that it was completely done updating. But now the iphone is not working at all. What do i do to fix it?|||first press and hold home button and then sleep/wake button all at same time make sure u do home button half a second first