To format the pendrive of any responce try this procedure:
Start > Run "cmd"
type-> list volume
type-> select volume #
the the pendrive is clean but u cannot access the pendrive or u cant format directl.
it will displays the formating error.and file partition is soo big.
so now follow these steps:
step1: right click on my computer
step2: click manage
step3: click disk management under storage
step4: goto to ur volume and right click on it and slect make new partition
step5: click next many times until it finish
this might help you out ... let me know