Forget the WD, you will really be screwed if you use that. If it gets past the keyboard and onto the motherboard, you will need alot more. I don't want to go into the chemical properties of WD40, but you do not put it on circuit boards usually.

Laptop keyboard are not unique like little snoflakes and ****, you CAN buy them. If the thing is a couple years old, someone could have one on eBay with a broken screen or something. That **** happens all the time.

Simply one letter on a keyboard ? I would certainly pop it off and have a look underneath. If it doesn't work you got nothing to lose. Usually thwey pop right back on. Right now my "J" key takes a hard hit to work, but I just happen to have a replacement keyboard for theis laptop. I kinda got lucky that way. It is a full size with the numeric at the right. If you have that type expect to pay a few more bucks for a replacement.

Of course you can just plug in a USB one. Hell, they gotem that roll up now..