How to fix a Black screen on my IPhone 4?

My iPhone 4 was somewhat updating I guess? But it just shut off on me & keeps on turning on & off to a black screen with a apple logo. I try holding down the home button & the top but it keeps doing the same thing. It's been like that since last night & today it's still acting the same. How do I get it back to working normally again instead of just a black screen with an apple?

Hold the center button and power button at the same time until it restarts it might work but i dunno. It should bc it worked with mine… If it doesn't then just look up stuff on the internet for frozen iphones… I'm sorry if none of this helps… I hope it helps tho ^.^