How to unblock my iphone 4

Hi.

After remotely locking my iphone 4 via 'Find my iphone', I need to unlock it.

On my handset it says 'iphone is disabled, connect to itunes'. The itunes that I originally synced it with, is on a computer I no longer own. After signing into my itunes account on a different computer, when attempting to unlock it, a message reads 'itunes could not connect to the iphone because it is locked with a passcode, you must enter the passcode on the iphone before it can be used with itunes.' However the original message on the handset remains.

How can I unlock it without my original (default) itunes that the phone was synced with?

Thank you.