Plug-in your Flash Drive. First plug-in your USB stick to your USB port and copy all the content to a safe location in your hard drive .
Run Command Prompt as an administrator. To open a command prompt, go to the Start menu and search for CMD. Right-click on it and select Run as Administrator to use it with admin rights.
Using the Diskpart utility find the drive number of your flash drive. To do so, type in the following command in the command prompt: DISKPART Running DISKPART will display the version of DISKPART you are running and the name of your PC.
Type “list disk” to see a display of all your connected disk drives. Make a note of the number assigned to your Flash drive.
Format the drive. Execute the following list of commands one-by-one. Make sure you replace Disk 1 with the proper Disk number from DISKPART.
select disk 1
create partition primary
select partition 1
format fs=NTFS QUICK
Make the flash drive bootable. Use the bootsect utility that is shipped with Windows 7/Vista. To do so: Insert the Windows 7/Vista DVD and note down the drive letter of the DVD drive. For this guide, the DVD drive is D: and the USB drive is G:.
Navigate to the directory where bootsect is found. D: cd d:\boot
Use the bootsect to make the USB Drive bootable. This updates the drive with BOOTMGR compatible code and prepares it to boot Windows 7/Vista. BOOTSECT.EXE/NT60 G: