Original post : Refresh or Reset Windows 8 Without Installation Media.
You need to have the installation media or the original ISO file (from your Microsoft account) to configure your system. Afterwards, you can refresh or reset Windows 8/8.1 without the installation media.
Some files are missing. Your Windows installation or recovery media will provide these files.
reagentc.exe /setosimage /path C:\Win8 /target c:\Windows /Index 1
REAGENTC.EXE: Operation Successful.
recimg –CreateImage C:\Win8Image