recover pen drive data

Hi,
i have a 4 gb pen drive, with very important data in it. But suddenly i got a message that ''it need to be formatted before use''.
i understand that pen drive is corrupted, i tried to recover data by many softwares but they cannot recognize the partition as well.
I thought that a format might be solve that issue....
But after format pen drive works and data cannot be seen/recover by any software at all.
I again say that it contains very important data and i dont want to loss it, so kindly show me a way plssssssssss.............

I would try a program called Recuva, but I would not expect to get much data back now that the flash drive has been reformatted.