Just a tip, my truck key has been sticking a little for years now, but today it got so bad I couldn't open either door. I borrowed Kyla's key, and it didn't work either.
My first thought was that the key was just old and worn down, but then I thought -- "Hmm, why would both keys be worn down, since mostly only my key gets used? Maybe it's the tumblers in the door part? But then why wouldn't the keys work on either side?"
Then I realized, "Ah! Maybe one of the pins is just stuck in there!" So I put some 3-in-one oil on the tip of my key and pushed it in and out a few times, and voila! Now both keys work perfectly in both doors.
Hope that helps somebody.