My kingston flasdisk is write protected , i can't copy any data and backup . size: 8 GB

What you need to do is connect your usb drive, then open a command prompt window (Programs->accesories) and in this window type:

diskpart.exe
and press enter

you will be presented with another window similar to the first. In this new window type:

list volume
and press enter

this will show you a list of all drives connected to your machine.

Next type:
select volume *


where * is the volume number of the required drive listed in the list volume section.
and press enter
This will select the drive for the change you are about to make.

type:
detail volume
and press enter

this will list all of the attributes to do with the selected drive, you should see in there that the disk is write protected.

next type:
ATTRIBUTES DISK CLEAR READONLY
and press enter. Once the window has finished what it's doing you can close all of the command prompt windows and your disk should be ready to use again.

Hope this wasn't too long winded and has been of some use to you.