Ever wanted to format your PC and suddenly you remember that you’ve lost your Windows 7 disk or you find out that it’s all scratched and having problem to make it work. What next? You’ll buy another disk or get it from your friend. To help you from future problems, I am here with a step by step tutorial to guide you through the steps to make a bootable Windows 7 in Flash drive.
You may be wondering why flash drive instead of CD/DVD. The answer is clear as I’ve mentioned it above, i.e. just the minor scratches fail your DVD to work properly. Moreover if you don’t have DVD drive or you have a netbook then this trick might come pretty handy. Plus, reading data from flash drives consumes less energy resources as it doesn’t need any mechanical device to read as in DVD.
But another question may arise, DVD are cheaper than flash cards. Sorry folks but I have no answer for this. However you’ll realize its need when you really don’t have any resources to install Windows. Anyways let’s begin with the tutorial. Make sure that you have a flash drive not less than 1 GB space and also you’ll need Windows 7 installer disk or iso image. Oh yes, and you must have administrator’s privilege.
First thing to do is obvious; insert your flash card in to your computer. Since Windows 7 setup can only be booted in NTFS format, you’ll need to format your flash drive in NTFS format with any volume label.
Run command prompt and in command prompt, type diskpart.
The disk partition manager will run in DOS mode.
To check the existence of your flash drive type “list disk” (without quotes). It will list all the volumes even the hidden one with the volume name.

Remember the disk number and disk space for the identification purpose. In my case it’s disk 2. Select disk by using following syntax.
Select disk #
Where, # is the disk number.
If the disk is selected it will say that disk 2 is selected.
Type, clean to clean the disk. It will notify you when its done.
Now type create primary partition and press enter. If you got confused, then refer to the following screen:
Now list the partition by using following syntax:
list partition
The partition available will be listed. Now with the help of disk space you noted previously in select disk. Remember the partition number.
Type select partition # . While # is the partition number.
If selected, the partition number is selected message will be showed.
Now type activate, to activate the partition.
You’ll get similar result as the image below:
Now you’ll need to format the drive in NTFS format by using following syntax:
format fs=NTFS
Wait until the format is complete.

After the format is complete, type assign.
Now you are done with diskpart. Type exit and press enter to exit.

Now insert Windows 7 disk or extract the iso image to your hard disk with the help of 7-zip or similar extraction software.
Now in command prompt change the directory to root location of your Windows installer. If its DVD then it might be the drive letter (in my case it’s F drive). If you have extracted it to a directory then load command prompt from there.

After you are inside the boot folder, type the following syntax:
bootsect /nt60 Z: (Where, Z is the drive letter of your flash drive)
If everything went well you’ll see the following screen:
Now, copy all the files from the Windows 7 DVD or ISO to the flash drive.
Reboot the computer. Remember to change the first boot device to your Flash drive in the BIOS.
You should be able to install Windows 7 from your USB flash drive now.
Hope that was helpful.
Update: If you don’t want to go through these mess then Microsoft has released a utility for this, you can download it from their site.
Windows 7 USB-DVD tool
Instruction