my pendrive is no working why

Or, you expect it to auto-open and it does not?

Or, you receive a device not recognized error?

Which OS?

Preliminary hints:
http://www.online-tech-tips.com/computer-tips/usb-device-not-recognized/
http://support.microsoft.com/kb/871233

Or, is it that you simply cannot access data on the drive? In that case, did you Safely remove the device last time?

Maybe it still works.

The first time you connect a specific pen drive to your computer, it will automatically install the drivers needed for the drive.
Next time you connect the same drive, no installation is needed.

Depending on settings in your computer, it is possible that the computer won't ask what to do when a drive is connected. In that case, the drive will show up in Windows Explorer, even if no dialog pops up.

It is also possible that group policies restrict the computer from talking either installing new usb drives or communicate with usb drives altogether.

Further, if you disconnected the usb drive without first ejecting it (safe removal) then there's a risk that the information structure of the drive was damaged.
Try checking the status of your pen drive in the disk management tool (diskmgmt.msc).

Finally, of course we can't exclude that the drive is damaged. Since it's completely new, you could try claim warranty.