Dropped iphone onto concrete now won't turn on - fails to restore in itunes

So my phone has slipped from my hands & dropped a good 10 metres or so onto concrete.

The screen has not cracked so I'm guessing it's a hardware issue.

I have tried reseting it by holding down the lock button + home button for a good 30 seconds though this appears to do nothing at all.

In itunes it will come up as being detected in recovery mode & that I must restore it, which I have tried several times & it results in the message " The Iphone could not be restored. The device cannot be found"

Is there any thing I can try to have this fixed or is it completly screwed? It will also continuously appear/dissapear from itunes.

Thanks in advance for any help given.