How to make Windows 7 bootable install USB stick

How to install windows from usb flash drive
Please note: during this procedure you'll lose any data on your USB flash drive. Please be extra careful during formatting, choosing the wrong drive will erase it completely. This guide provided as-is, at your own risk.

You will need:

PC running Windows XP/Vista/7/8/10
USB drive with at least 8GB of free storage

Preparing the USB drive:

Open command prompt as administrator - Right click on Start > All Programs > Accessories > Command Prompt and select Run as administrator or type cmd in the Start search bar.

• Type diskpart.
• In the new command line window that opens, to determine the USB flash drive number or drive letter, at the command prompt, type list disk, and then click ENTER. The list disk command displays all the disks on the computer. Note the drive number or drive letter of the USB flash drive.

• At the command prompt, type select disk <X>, where X is the drive number or drive letter of the USB flash drive, and then click ENTER.
• Type clean , and the click ENTER. This command deletes all data from the USB flash drive.
• To create a new primary partition on the USB flash drive, type create part pri, and then click ENTER.
• To select the partition that you just created, type select part 1, and then click ENTER.
• To format the partition, type format fs=ntfs quick, and then click ENTER.
  
  
  IMPORTAN:If your server platform supports Unified Extensible Firmware Interface (UEFI), you should format the USB flash drive as FAT32 rather than as NTFS. To format the partition as FAT32, type format fs=fat32 quick, and then click ENTER.

• Type active, and then click ENTER.
• Type exit, and then click ENTER.
• Now we have prepared USB drive. Lets make it bootable:
• Insert Windows 7, 32/64-bit installation disk into DVD drive. Let's assume it's D

Copy DVD Windows 7 media content to USB root folder (etc. don't put it into any folder)

You are now ready to install Windows 7 from USB flash drive!
JUST Restart your computer AND FROM THE POP UP BOOT MENU SELECT  USB FLASH DRIVE
You can Watch this tutorial