Windows file repair command?

[Capt. Picard]

I can't remember the run command because I did it so long ago, but I want to repair a windows file. I've done it once or twice before where I typed in a command in "run" and it scanned the windows CD for the original file. What is that command?

[rewt]

sfc /scannow

I usually do a sfc /purgecache first, but might take longer because it clears out the entire dllcache.