iphone 4 stuck in recovery mode itunes unable to detect it

i was in ios 4.2.1 and i tried to update to ios 4.3.2,half way of the upgrading, itunes shows and error(i cant really remember whats the error,it contains numbers actually) and now it stucks at the recovery mode...i have tried to use tiny umbrella to exit the recovery mode. the worst thing is that i tunes and tiny umbrella are unable to detect my phone.i have tried to restart by pressing home button and sleep button,it does not work as well.so what am i going to do now to get my iphone 4 alive?