I can't unjailbreak my iphone?

So my father gave me an iphone which was originally his and it's been jailbroken it has Cydia downloaded, what do I to make it run normal and to have the proper software. I've tried restoring it in itunes but it says the Device isn't eligible for this download or something like that.
I think it's an Iphone4 it says its a version 6.0.
not sure what to do?

I don't think an "old" phone like the iPhone 4 can run the modern ios 7.

You need to tell your dad your F'd up if you were not suppose to screw with his phone.

  • Would I still get my warranty if I unjailbreak my iphone 5? I heard if you have an jailbroken iPhone the company won't fix it phone, if anything would happen to it.
  • Why can't I unjailbreak my iphone 5? I want to update to 6.1.2 but I'm jail broken with evasion and when I connect if go my computer to restore it takes a long time to load and says that it's up to day or something and when I check my software update on the iPhone it never loads and when I tried resetting it it never finishes what can I do? How do I unjailbreak when nothing's working
  • What will I lose if I unjailbreak my iPhone 4? So I have had my iPhone jailbroken for a while and now i want to update to IOS6 and just simplify my phone, how do i unjailbreak it and what will I lose if I do, I just don't want to lose message history and photos.
  • Should I unjailbreak my iPhone 4? Should I? It's slowing down and i don't want to mess it up anymore. Should I unjailbreak it?