Check your security software
Errors: 2, 4, 6, 9, 1611, 9006.
Sometimes security software can stop your device from communicating with either the Apple update server or with your device.
Check your security software and settings to make sure that they aren't blocking a connection to the Apple servers.
If you still see the error message, check for USB connection issues.
If you do not have a backup, then your chance of recovering is nil.