Install Windows 8 / Windows 8.1 from Pen Drive/USB Drive/Portable Hard disk

Ever wanted to install Windows 8 / Windows 8.1 / Windows 7 / Windows Vista From USB Drive/Pen Drive due to non availability of DVD/DVD Drive. Follow the Steps Below to create a bootable USB Drive.

This tutorial below is applicable for Windows 8 / Windows 8.1 / Windows 7 / Windows Vista or we can say windows with vista bootloader.
To install windows from USB Disk Drive(PEN Drive) you first need to confirm if your system support boot from USB Disk Drive. You can find these setting under boot settings, boot priority.

Here is the step by step tutorial on how to create Windows bootable Pen Drive/USB Drive/Portable Hard disk:

1. Insert your USB Drive to the system and backup all the data from the USB Drive as we are going to format the USB Drive to make it as bootable. 
2. Open elevated Command Prompt. To do this, type in CMD in Start menu search field and hit Ctrl + Shift + Enter. Alternatively, navigate to Start > All programs >Accessories > right click on Command Prompt and select run as administrator. 
3. When the Command Prompt opens, enter the following commands
   DISKPART and hit enter.
   LIST DISK and hit enter.
   
   Once you enter the LIST DISK command, it will show the disk number of your USB drive. Look at the size of Disk Drives. The Size Matching your USB Drive's size needs to be selected.
   (FYI 1024MB = 1GB) 
4. In this step you need to enter all the below commands one by one and hit enter. As these commands are self explanatory, you can easily guess what these commands do.
   
   SELECT DISK 1 (Replace DISK 1 with your disk number)
   CLEAN
   CREATE PARTITION PRIMARY
   SELECT PARTITION 1
   ACTIVE
   FORMAT FS=NTFS (Format process may take few seconds)
   ASSIGN
   EXIT
   
   Don’t close the command prompt as we need to execute one more command at the next step. Just minimize it. 
5. Insert your Windows DVD in the optical drive and note down the drive letter of the optical drive and USB media. Here I use “D” as my optical (DVD) drive letter and “G” as my USB drive letter. You can also use the DVD Image of Windows or Extracted Files. Extract all the files from DVD Image as well and use that location in next command.
6. Go back to command prompt and execute the following commands: 
1. Change directory to the DVD’s boot directory where bootsect lives:
   
   d:cd d:\boot
   
   
2. Use bootsect to set the USB as a bootable NTFS drive prepared for a Vista/7 image. I’m assuming that your USB flash drive has been labeled disk G:\ by the computer:
   bootsect /nt60 g:(Where “G” is your USB drive letter)
   [Note: If this command fails copy the content of DVD to your Hard Drive and repeat Point 6 again with new location instead of D:]
7. Copy Windows Files to USB Drive.

You are done with your bootable USB. You can now use this bootable USB Drive to Install Windows on any computer that comes with USB boot feature (Mostly motherboards support this feature).
Note that this bootable USB guide will not work if you are trying to make a bootable USB on XP computer.