Kingston Pendrive, write protect?

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Fcing o problem, kingston usb101DT pendrive, within 2 months, it become write protected itself. As a standard usb stick, it doesn't have a physical write protect button, and i didn't do anything such as making partition read only. Now it can't write anything into the pendrive and unable to format it. I am suspecting there's something odd for the partition become broken. Anyone else know the cause of problem?