Click on Start | Control Panel | Accessibility Options | Keyboard
tab | uncheck the "Use FilterKeys" and "Use StickyKeys" boxes | OK.

HilaryEvans wrote:

I've inadvertently turned on filter keys by holding shift key for over 8
seconds. Ever since I can't:
backspace quickly
type quickly
caps lock is turned on or off each time I press it without the caps lock
light showing on keyboard.

I've tried holding shift key down for 8 seconds again and have gone into
settings and tried all sorts of different combinations but I cant get back to
how things were before I activated this irritating thing. What are filter
keys anyway?