Error 1604 is an iPhone problem that shows when you try and restore your device to a previous / backup state. The issue you have here is that iTunes will typically be unable to correctly process the various important settings that it requires to make sure the restoration processes properly, and consequently will lead the error you're seeing to occur. The way to resolve the problem you're seeing is to first ensure that your computer has the ability to process the various backup options that your system has, as well as then make sure that your system has no problems with the settings it has inside.
What Causes The 1604 Error?
This error will typically show in this format:
The error you're seeing will generally be caused by the way in which your PC will be unable to read the restoration options / settings; and will therefore be vital that you're able to ammend any of the problems that your system will have in order to make sure this is okay.
How To Fix The 1604 Error
The first step to fix this problem is to re-install iTunes on your PC. This can be done by first clicking onto "Start", then selecting "Control Panel" and then picking "Add / Remove Programs". When you have loaded the Add / Remove programs panel, you should then look to remove the application that's causing the issues to show - a process that can be done by clicking onto "iTunes" and then "Apple Mobile Device Support", removing them from your PC.
After you've done removed iTunes, it's recommended that you clean out any registry errors that Windows may have. Registry errors are problems that are caused by Windows - leading your system to run much slower and with a lot of issues as a result. We've found that there are a lot of problems that will prevent the registry from running smoothly, and therefore you have to be ble to repair any of the files that will be causing it to run unreliably, by downloading a "registry cleaner" tool.
Our recommended program for this is one called "Frontline Registry Cleaner" - a leading product that's been designed by a large UK software company to get rid of the various problems that your system will have inside.