Many time we wish to reinstall OS but we can't due to failure of CD/DVD media or many reasons. However any USB drive can be used for installing Windows OS, off course, first you have to make it bootable. The method is very simple and you can do it yourself. Needless to say that your motherboard should support USB Boot feature to make use of the bootable USB drive. This method can be used for installing any version of Windows (XP, Vista, Seven)

Just follow these guidelines step by step:-

Step 1

Plug-in your USB flash drive to USB port and erase all contents.

Step 2

Open DISKPART with admin rights. Use any of the below methods to open DISKPART with admin rights.

*Type DISKPART in RUN box and hit OK.
Or
*Go to C:WINDOWSSYSTEM32 right click on DISKPART.EXE and select Run as administrator.

Step 3

Type LIST DISK command and note down the Disk number (ex: Disk 1) of your USB flash drive. In the below screenshot my Flash Drive Disk no is Disk 1.

Step 4

Next type all the below commands one by one. Here it is assumed that your disk drive no is "Disk 1".If you have Disk 2 as your USB flash drive then use Disk 2. Refer the above step to confirm it. So below are the commands you need to type and execute one by one:

SELECT DISK 1
CLEAN
CREATE PARTITION PRIMARY
SELECT PARTITION 1
ACTIVE
FORMAT FS=NTFS

(Format process may take few seconds)

Open Command prompt (with Administrator privilege)

Step 5

Next insert your Windows7/Vista DVD into the optical disk drive and check the drive letter of the DVD drive. Here, I am assuming that our DVD drive letter is "D" and USB drive letter is "H".

Step 6

In command prompt, type D: CD BOOT and hit enter. Where "D" is your DVD drive letter.

Step 7

type CD BOOT and hit enter.

Step 8

type BOOTSECT.EXE /NT60 H: where H: is your USB drive letter. Wait for message same as below.

Now copy your Windows 7/Vista DVD contents to the USB flash drive as we do normally. Your USB drive is ready to boot and install Windows 7/Vista. Only thing you need to change the boot priority at the BIOS to USB from the HDD or CD ROM drive.

Note: If you are not able to boot after following this guide means you haven't set the BIOS priority to USB. If you got any problem in following this guide feel free to ask questions by leaving comment.