How to restore my Iphone without getting an itunes error?

Basically I had a battery issue with my Iphone and was told to restore it before sending back. I couldn't restore it as I kept on getting an error message so I was told by a friend to put it into DFU mode. I did this and but now in order to take my phone out of recovery mode I must restore it and I keep getting the same error message. "The Iphone can't be restored at this time because the iphone software update server could not be contacted or is temporarily unavailable".So I now own a very expensive brick that I can do nothing with. Someone please help? I tried editing my hosts file but it looked completely different to examples and did nothing (not sure if I did it right). Note my phone is not jailbroken (Iphone 4S)

Right have you got the newest version of itunes? If not then please download it and that may well sort the problem out right away.
But if you are running the newest version? I would suggest if you can using a different computer to do the restore on! I used to have a computer that for some reason would never complete a update or a restore on my iphone it used to drive me crazy, but i was told by the apple store to try another computer which i did and it restored straight away with no problems at all.