iphone frozen on connect to itunes

can anyone help me? I bought a second hand iphone 3gs that was unlocked and jailbroken and did not realise I could not restore it on itunes and it has now frozen on the connect to itunes screen. I was told that it is locked and that I needed to get a sim card from the network the phone was originally on (Rogers), which I did but it is still frozen. Does anyone know what I can do? Any help would be greatly appreciated!
lifebook s6120 Windows XP Pro