How to create a Windows 7, Windows 8 bootable USB/Pendrive

There are lots of guidance you can get from google to make a bootable USBdrive. But be careful ! They can lead you to a corrupted OS or USB drive.

This procedure is safe and you can install Windows faster than discs and without any hassles.

Requirements:

1. USB Drive (Minimum 4GB)
2. Windows installation files. You can copy this files in your machine from the windows CD/DVD.

Procedure:

1. Go to Start menu > All programs > Accessories, right click on Command Prompt and select Run as
administrator.

2. Now type the following commands one by one
 
You will now enter into the DISKPART utility.
    i)  DISKPART 

Now note down the Disk number (eg: Disk 2) of your USB flash drive. In the below screenshot my Flash Drive Disk no is Disk 2.
    ii) LIST DISK

Select your USB disk
   iii) SELECT DISK 2

Clean the disk
   iv) CLEAN

Create a primary partition in the USB drive
   v) CREATE PARTITION PRIMARY

Now select the partition
   vi) SELECT PARTITION 1 

Make the partition as active
   vii) ACTIVE

Attention: This process can take almost an hour to format depending upon the size of the USB drive. Better right click on the USB drive and select NTFS and Quick format. And don't execute command no. viii)
   viii) FORMAT FS=NTFS

After completing FORMAT now Assign it and exit from DISKPART utility
   ix) ASSIGN
   x)  EXIT 

Now you'll again come back to C:\Windows\system32>. Don't close the Command prompt just minimize it.

3. Now the actual location of the Windows installer files could be a CD/DVD or it can be in your Local Disk)
I assume it is in CD/DVD and the drive then the path should look like F:\boot (Drive can be anything D, E as per your machine)
Or if it is in Local disk then I assume the path  looks like :   D:\<windows7 folder>\boot 

4.  Now again maximize the command prompt. and got to the \boot  folder location

     C:\Windows\system32> cd F:\boot
     F:\boot> bootsect.exe /NT60 G:

Where G: is your USB drive letter (in my case). We are actually updating the USB drive with the BOOTMGR. 

5. Now Copy the Windows installer files in the USB drive.

Your Bootable USB drive is now ready. From BIOS change the boot order to USB and install Windows.