How long would it take to someone who doesn't know to play a piano, to learn Mozart's Rondo Alla Turca?

Well, I'm guessing if you don't know how to play piano (and I'll ume that you're not any other type of intrumentalist, because you can't read music), it'll be damn near impossible. Let me tell you why: you don't have a developed enough ear to learn everything in the piece. My suggestion is to learn to read music and study the piece for yourself. It'll be much more rewarding than taking a year to sound it out and ultimately, not learning it correctly anyway.