How to create a Bootable Windows 7 or 8 USB Flash Drive manually

What you need and things to keep in mind

1. A 4GB (or more) USB Flash Drive is required, if needed for Windows installation.
   
   
2. A Windows 7 installation directory, or a .ISO image of Windows 7.
   In case you have a .ISO image, an extraction program is also required.
   (DAEMON Tools Lite is free for that purpose)
   
   
3. Make sure you motherboard is capable of booting from USB,
   or else your computer won't be able to make use of the bootable device.
   
   
4. This tutorial is suitable for Windows XP operating systems, where there is no bootsect utility.
   A guide using bootsect is also provided.

Creating the Bootable device

1. Plug-in your Flash Drive to the USB port.
   
   
2. Run Command Prompt (cmd) as an administrator.
   
   
3. Type "diskpart" and hit Enter.
   
   
4. At the Diskpart utility type "list disk" and hit Enter. Check your Flash Drive's Disk Number.
   Please note that number. (Let's assume, from now on, that the USB Drive is "Disk 1")
   
   
5. Format the drive by executing the following commands one by one:
   (be careful not to forget to replace Disk 1 with the proper Disk Number)
   
   sel disk 1
   clean
   create partition primary
   sel part 1
   active
   format fs=NTFS
   assign letter=Q
   exit
   
   
6. Close cmd.
   
   
7. Make the Flash Drive bootable.
   
   • Without the bootsect utility
     
     a. Mount the .ISO, to create a Virtual Drive.
     
     b. Copy and paste all files and folders from the Virtual Drive to the USB.
     The same applies for those who have a Windows 7 installation directory.
     
     c. Unmount the .ISO
   • Using the bootsect utility
     
     a. Mount the .ISO, to create a Virtual Drive.
     Let's assume that the drive letter for the Virtual Drive is "F:" and "Q:" for the USB.
     
     b. Open cmd and type "F:" and hit Enter. Then type "CD BOOT" and hit Enter.
     
     c. Type "BOOTSECT.EXE /NT60 Q:" and hit Enter.
     
     d. If done properly, you should get a message implying
     that the Bootcode was successfully updated. (the USB is now bootable)
     
     e. Close cmd.
     
     f. Unmount the .ISO
8. Un-plug the USB and you are good to go.

 

I use a little program called Rufus, it does the magic with a few clicks!