the letter e,,o(h) great one
Ah......I'd lever it off carefully (it'll be held in with a pair of tinyplastic clips probably....try and lift it vertically rather than levering it at an angle IYSWIM
Then get a cotton bud and some spirit (Nail varnish remover, acetone, contact cleaner, fekkit, petrol if you've not got anything else) and clean the contact/microswitch and see if that helps.....
Might also be worth looking at the back of the unit to see if it comes off....you'll find half a Digger in there in fingernail scrapings, fluff, dead skin and beard hairs (we'll call then beard hairs to save your embarrassment but we all know that one handed surfing could be involved in this blockage
)
and again, you can clean it all out.
You're not daft enough to use spirits/petrol without testing it on the plastic first, so don't blame me if later on, you've got a melted laptop
(a slightly damp cloth may be a more sensible option)
Chances are it's fixable, but if not, Tesco value keyboard, £4.99.....you should be able to plug that in (usb) and it'll work.
