you may have stepped on a key and held it too long therefore activating the Sticky or filter keys or other optional keyboard settings. Try this first before you get into all the hardware fixes: Method 1: Disable the Filter keys and check if it works. a: Type Ease of access in the start search box and hit enter. b: Now click Change how your keyboard works c: Remove the check mark from the box next to Turn on FilterKeys. d: Click the blue Set Up FilterKeys link e: Underneath Keyboard shortcut, remove the check mark from the box next to Turn on FilterKeys when right SHIFT is pressed for 8 seconds. f: Now click Ok two times.