My Iphone four crashed mid update and now won't restart?

I downloaded the latest update, and in the middle of it, my phone shuts off. Now, whenever I turn it on it just says plug into itunes, and I can't do anything else. It says I need to restore to original factory settings and lose all my data, which I Really don't want to do. Does anyone know if there's a way to solve this so I don't have to lose all my data? Yes I have apples site and they only have one thread about it for the recent crash and it is unanswered.

I'm not 100%right but there's 2 ways of problems. One is you have a very slow internet connectivity and two is you downloaded more that halve of your spaces. If not of above, it means that last est update does not support iPhone 4. I had a iPhone 4 but I also can't install the lastest version. I will try to find more solution but you have to reply to me that either not of above or one of the above.