If you don’t have optical drive installed on your laptop,you can create a bootable windows 7 usb from your windows 7 installation iso using Microsoft’s Windows 7 USB/DVD download tool. Altnatively you also can create a bootable usb from iso using 3rd party tool such WintoFlash which also support Xp and Vista
1.Download Windows 7 USB/DVD download tool
3.Insert your usb disk or pen drive(4G+) to your laptop and backup your data to a safe place because this tool will format your usb drive
4.Launch Windows 7 USB/DVD download tool,In the SOURCE FILE box,click BROWSE and select the file from the OPEN dialog box. Click NEXT.
5.Select USB DEVICE to create a bootable windows 7 usb or select DVD disk to create a copy on a DVD disk.
6.Select your USB device in the drop-down list then click BEGIN COPYING.
7.Now the tool will begin to create a bootable windows 7 usb from iso for you,this will take a while
7.Done.And now you can change the boot order of drives in your BIOS to boot to windows 7 from this bootable windows 7 usb