My pen drive is 8gb but i think bad sectors there in my pen drive so working only 2gb what i do

There is no way of doing this. If your pen drive is 4GB, that means it has only 4GB of memory chips in it. The only way to get 8GB is to buy an 8GB drive. Do not buy an upgraded (to 8GB) one, as they are lower memory ones that have had the firmware tinkered with to show 8GB, when the actual memory capacity is far less.
18.January.2015

click start control panel administrive tools,computer management ,disk management right click on your drive select properties click tools you should see click check now click start two boxes automatically fix files and scan for and attempt recovery of bad sectors place then a tick in both boxes then select check now,start should schedule this task when restart or you might tick one box then return after its finished the first repair the tick the second box
hope this helps

you can take off write by util disk that it came with or read manual it should say jim

Many times the pen drive can not be formatted or is not detected. If these problems occur and according to what you describe,The pen drive you are using has corrupted memory sectors. Its of no good use, if under warranty, go for a exchange from the service support or else Buy a new pen drive.

Hi,

Go to Disk Utilities and reformat the pen drive. That might do the trick.

All the best!

It seems that the drive may have corrupt data sectors. Unfortunately this is not generally repairable with flash memory, and you should take the pen drive back and have it replaced under warranty.

Yes first you need to recover your data so yo must use a tool to do that, maybe the "Pen Drive Data Recovery" can help you, I think it free you must search for it at google, and then when you stract your information you might use a Low Level format tool to get you're USB flash drive working again such as the hdd-low-level-format-tool, you can find these two tools at google

CHECK VIRUS with an updated vitus remover.

On first read, the error message indicates that there is a bad section of the flash memory card in your pen drive. We call these areas, sectors. A utility in Windows, called ScanDisk, which you may be familiar with can scan and then mark the sector as bad and then allow data to be written again.

However, this may be a fatal error and render the flash drive unusable. I'll have to ask you to check a few things to make a final judgement.

First, when you insert the pen drive into a usb port, does Windows recognize the drive by making the familiar tone or do you get an error message on insert?

Thanks for taking a few minutes to answer these questions. I'm afraid I will only have more until we can determine if you have a usable pen drive or not.

Just so you know, this pen drive has a lifetime warranty so it will be replaced and I can provide you with the web site address for doing that should it come to this.

Regards,
Worldvet

Try to right click the pen and select properties and check out the check box in the write protected