Need to downgrade to iOS 6. Help please

Hello,

I've done something stupid and need your help please. I have an iphone 4s, was using IOS7 but decided to go back to IOS6. I clicked erase data on my phone, now when i connect it to iTunes I get the message"We’re unable to complete your activation.
This device is not registered as part of the iPhone Developer Program.If you are a member of the Program, please register your device in the iPhone Developer Program Portal."

Would appreciate any help. Thanks

 

Thanks. In the process of restoring it now. Hopefully be all okay.