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.