Hi ! Search around but dont have the answer.

I brought my iphone from Maxis. Jailbreak it d and been using it for few months without problem but today my phone hang on the springboard and there are no icon on the page at all. I cant turn it off at all even plug in the cable, use itunes to sync also freeze at the springboard.
Anyone can help me ? If i restore back, will the itunes update the latest version 3.1.3 on its own?? Please help.