how to make a bootable USB with the help of CMD.You can Make Bootable USB of Windows 7/windows 8 by Command prompt. Follow these simple steps.. 

>Insert your Pen drive and press the start button.

>Type cmd and right click on it and start this with administrator right.

>Now on the command prompt, type the following commands

->Diskpart

List disk

// List disk command will generate the list of Disk connected to your computer like Hard disk and USB disk. This will be like in figure.

After this

->Select disk 1 // in my case USB it is as disk 1

->Clean

->Create partition primary

->Active

->Format fs=ntfs quick // Format File system=NTFS quick(don’t use Quick for deep format, just use format fs=ntfs)

->Assign

->Exit

Now copy all the files of Bootable CD to pendrive.

Just reboot your computer, enter in BIOS setup and select boot device priority as

* USB

* HDD

* CD/DVD

* Network (Other)

And Tap [F10] to save and Exit.

Enjoy.......!!!