What could be simpler than a computer keyboard? Just tap the keys and the characters appear. Ya think?
I've had a few gremlins in my computer of late, and the latest decided to move some keyboard functions around. Hit 
SHIFT and 
2, and get 
“. Likewise, hit 
SHIFT and 
“ and get 
@. 
# ended up on 
SHIFT and 
, while 
£ (which isn't even marked on this keyboard) popped up above 
3.
Maybe I'd accidentally hit some sort of bizarre function swap key. I tried for several days to fix this on my own – idiot!
Then a pal emailed me these pearls of wisdom: “You might need to look in the control panel under keyboard.” So, technofool that I am, I flipped over the keyboard 
and looked for a little control panel! Seriously – and I'm not even blonde!!
Then I googled 'keyboard problems' and found many people globally had the same problem. One UK site 
(Cherry Keyboards) explained I'd somehow changed the nationality/functionality that the computer recognised! I needed to change everything from US to UK...but when I reached Instruction Step 8, I discovered my computer's 'keyboard layout/IME' settings had NO option to choose English over US!
Then a light went on: change all the settings back to US, you prat! And with a huge sigh of relief, everything returned to normal! So if this happens to you, that's a probable solution.

...or maybe think about getting a blonde rinse!