You can use the Windows 7 USB/DVD Download tool, to create a Windows 7 / Windows 8 / Windows 8.1 bootable USB device.
You can download it here
Unfortunately sometimes you receive an error :
The Selected file is not a valid ISO file. Please select a valid ISO file and try again.
This error means that the ISO file is not fully compatible with the standard.
An ISO file consists of 3 things:
1. ISO 9660
2. Joliet
3. UDF
To solve this problem you can use PowerIso
Open PowerISO
Open the ISO file: File => Open => browse for the iso, and click open
Click on file => Image Properties
Select all 3 options : ISO 9660 / Joliet / UDF => click OK
Click File => Save
Click Yes on the question to overwrite the existing file.
Wait a while.
You can now close PowerISO and retry Windows 7 USB/DVD Download tool
Select your Windows 8.1 ISO file via Browse => click Next
Select ‘USB Device’
Select the correct USB Device and click ‘Begin Copying‘
Select ‘Erase USB Device’
Click Yes, to erase the USB Device
Wait until the copying is ready, and enjoy you Windows 8.1 installation !
