Any piano players out there?

As some of you may know, I've been working on playing piano again, after quitting at the age of 11 or 12 (I don't even remember...it was sometime in middle school). The books I have are for kids, and I'm now 17, so it is sort of frustrating playing books written for 6-9 year olds (or something like that). So, I am looking for a teach-yourself piano book that is not for children. Any suggestions?

Thanks in advance!