Go to Microsoft's page for upgrading to Windows 8 with a product key, then click on the light blue "Install Windows 8" button.
Launch the setup file (Windows8-Setup.exe) and enter your Windows 8 product key when prompted. Continue the setup process until it begins downloading Windows 8.
Close the Windows 8 setup window and confirm that you want to quit the setup.
Back at the Microsoft upgrading to Windows 8 with a product key page, click on the light blue "Install Windows 8.1" button this time.
Launch the setup file (WindowsSetupBox.exe), which will begin downloading the Windows 8.1 ISO
Once the ISO finishes downloading, the installer will take several minutes to check the download and uncompress the install files. When you're prompted to choose an installation option, pick "Install by creating media."
Decide whether you want the installer to create USB flash drive media, or save the ISO file.
If the issue is still not fixed, it can be a very critical problem with your computer affecting your personal data and the Windows Operating System. You will have to chat with our Experts or you can check with your local technician to get the problems fixed with very high priority.