How to clean a dirty flute [duplicate]

Question

I have recently gotten an upgraded flute but I kept my old one as well. I completely forgot about the old one and left it out, sitting on the piano for a few months because I forgot to put it back in the case and I didn't think I would ever have to use it again. But now that I'm in the Marching Band, I can't use my new flute because it would get too dirty being outside all day and some of my friends in band who were in it last year told me that Marching Band completely ruined their flutes. Anyway, my old flute is sticky and kind of brownish in most spots and I used silver polish on it and it worked for about a week but then it went back to the way it was even though I cleaned it. Is there any way that I could clean it and keep it clean at least until Marching Band is over?