How to protect a USB pen-drive from being formatting please reply soon if you have an answer
I have tested bit-locker , drive encryption but it's useless

Protect the device from being formatted by whom exactly?

Protect the device from being formatted by whom exactly?

if someone asked for my usb, i don't want that he could format my usb

Or you could say no, just saying.

Or you could say no, just saying.

sometime it'z not possible

I don't think you can do that. Encryption is possible but protecting it from being reformatted is something i have never heard before. Maybe you can try changing the write permission for the flash drive.

if in a worse case ,some formatted it and passed it back to you ,it would still be possible to retrieve the files using a program like recura .if your drive has really important file on it you shouldn't be lending it anyway ,also if if the files are really important they should be backedup on dvd's ,also thumb drives are so cheap now just buy one for lending ,unrelated but i own about 7 of them
http://www.piriform.com/recuva/download

In a Nutshell: You can't protect flash drive from being formatted by other people;)