To download a Windows 8.1 ISO from Microsoft, click here.

Once you have the correct ISO, mount it in Explorer (can do this natively on Microsoft Windows 8.0+), verify the drive letter, verify Image.WIM in the Sources directory. The ISO will need to be a standard deployment variety that contains Install.WIM in the Sources directory, otherwise the process will fail. In many cases now due to some changes Microsoft made, you'll need to have a copy of the OS ISO available.You can attempt this on any OS from 8-10 by using the following command in elevated CLI: DISM /Online /Cleanup-Image /RestoreHealth In some instances, you won't need the OS ISO to perform the DISM image cleanup.We will utilize DISMfor this next repair option. If CHKDSK and SFC fail to repair the issues with the system, then it this is your next option and besides restoring from a previous backup might be the second-to-last option before re-installing the operating system. This has since been advanced to more closely match Windows 10/Server 2016 repairs but with the below information I hope to guide you through performing these advanced tasks more easily!

In all honesty, before Windows 10 implementation, this was arguably the easiest OS to repair for a couple of years by running more basic commands. Further improving on previously deployed OS repair methods, Windows 8, 8.1, Server 20 R2 further allowed advanced repair where an in-place upgrade or total re-install would be required on previous operating systems.

Windows 8 attempting repairs