Now type the following commands (Press enter key after each command).
diskpart. This is to open the disk partition program.
You can see disk’s listed there. Note down the disk number of your pendrive eg. Disk .
Now type SELECT DISK X (where X is the number you noted down for the pendrive from step 5)
Now type CLEAN.
Now type the following commands by pressing enter after each one.
CREATE PARTITION PRIMARY
SELECT PARTITION 1 (Assuming your pendrive/ USB drive is 1).
EXIT(Now the disk partition program will exit). Now we need to give some more commands.
Now insert the Windows 7 Installation DVD and to your DVD drive.
Here i am assuming DVD drive as G and Pendrive as I.(Change it accordingly).
Now type G:CD BOOT
Now type this command BOOTSECT.EXE/NT60 I: to update your USB drive with bootmgr code.
Finally copy all the contents from the Windows 7 DVD to your Pendrive. Make sure you don’t cause any errors.
Plug / Insert your pendrive to your PC and restart the system.
Now Enter the Bios system accordingly by pressing the key delete.(This may vary some times it will be F2 or F12. It depends on the type of your system. Any how during the start up your system will display which key to press to enter the Bios).
Now select the USB/ Pendrive as the first boot driver.(Set the first boot priority to USB drive.).
Now save the settings in Bios and restart and you will be able to Install Windows 7 using that pendrive.
If you liked it make a comment . Feel Free to ask if you have any doubts. I will Try my best to Help You.