apple mobile devices

My friend recently gave me her old iPhone 4 (which is still in perfect condition as she was using it only a few days ago).

I plugged it into my iMac and it doesnt seem to be detecting the iPhone.

Ive tried absolutely EVERYTHING. Been sitting here for hours trying to restore it, I have re downloaded the latest iTunes,

I have gone through http://support.apple.com/kb/TS1591, http://support.apple.com/kb/TS3540, not to mention I have searched ALL OVER the internet for a solution but with no luck.

I have tried changing the USB chord its self as well as the ports, restarted dozens of times. Both the iPhone and the iMac dont seem to want to even achknowledge eachother.

I am losing my mind here does anyone else have this problem? Has any amazing person got a solution???

Thanks,

Finn