IPhone ERROR 21 after attempted restore, see below? Please?

Basically my phone died for no reason while i was on it, then the apple logo came up and that was all, after plugging it in via power point it told me to plug into itunes, after doing that it became clear all i need to do was restore it… Then when i began to restore it, Error 21 came up and eventually another number after that. I have tried, DFU mode, disabling all security systems, switching hosts files, updating all software and all operating systems, using a different laptop, then a different cable. And nothing, nothing worked.

I spent well over 4 hours on this, my iphone is a very important object in my life, even for work, and i don't know what to do, i don't have alot of money and wouldnt want to spend it on this because seems to me some people are managing to resolve this issue yet i'm not getting any further issues but the problem isn't cured. Help me please, needless to say i'm panicking and thinking my life is over. Its an iphone 4, i have a windows 8 laptop. Anyone for the love of God have an answer to this?

Why don't you go and get it checked in an Apple Store. In fact they may not actually want you to spend too much money anyways, if the problem is really Software related. Also remember that you are almost 3 generation behind and the active life (battery life etc.) of your iPhone maybe nearing the end.