Finder/Quicklook Bug (File Icon Previews Not Working) My Macbook has suddenly stopped generating preview icon of all file types. So all files are now replaced by their respective generic file type icons (see picture attached). Moreover, when I quicklook any file, the preview appears corrupted. 

I have not updated any software recently, nor have I modified any file systems. 

Any help would be much appreciated!
Per comment under original question, first thing I'd try (which turned out to be the solution) would be to run sudo qlmanage -r in a terminal, which resets the QuickLook subsystem.