Itunes 10.6 won't detect Iphone 4 on windows.

I need help please.

I have an IPhone4 on a very old 4.01 firmware. I just backed-up and tried to upgrade to the newest IOS and at the end, I got an error code at the restore stage. Now my iphone is stuck and my Itunes won't detect the Iphone at all so I can't restore it anymore.

I am running a windows OS. Itunes is updated. I went through ALL the steps suggested by apple (update itunes, restart computer, check apple mobile support, check usb, check battery, etc etc etc).

Now my Iphone is basically bricked and stuck, Itunes won't detect it despite every possible attempts.

Please help?