Back button doesn't work

The back button on my Kindle stopped working. When I press it, it doesn't click. I think that at one point I was putting on hand lotion and a drop of hand lotion fell on that spot. Although I wiped it off quickly, I'm thinking that it may have seeped through the cracks and that is what is causing the problem. My Kindle is out of warranty. I see that the Kindle can be taken apart, but I'm afraid to do so, because everything else works fine and I'm afraid that if I take it apart, I'll mess it up. Any ideas?