You’ll need to be connected online, as Windows will download clean versions of corrupted files and replace them. If you see the “Windows Resource Protection found corrupt files but was unable to fix some (or all) of them” error, type DISM /Online /Cleanup-Image /RestoreHealth.Take note of the space between sfc and /scannow. Type sfc /scannow without quotes and hit Enter.

Type PowerShell into the Cortana/Search bar, single-click on Windows PowerShell from the list if needed, then right-click and choose Run as Administrator or select it in the right pane.