Need a crash course in fourier analysis, recommend resources I need to be able to understand everything about fourier analysis asap. Could you recommend one or two references or books that are considered 'the book' to learn this subject?

Fourier Analysis: An Introduction by M. Stein and Rami Shakarchi is the book I'd recommend.
I used it to improve my knowledge of Fourier Analysis and I was quite satisfied with it. I think it covers the basic facts and also some rather special issues as for example Fourier Analysis on finite groups which is important in number theory.
