what is the best book to understand general,classic and modern physics ??
Although it's a bit out of date, here is a link to a reliable source which suggests some good ideas.
At what level? High school, introductory undergraduate, advanced undergraduate? Do you know basic differential and integral calculus, or only algebra and trigonometry?
If you have a chance, a good idea is to drop by a college library or public library and browse through many physics book and see which one you feel good with.
It really depends on the level at which you're wanting to learn it. An introductory general physics book will cover all of classical mechanics, electricity and magnetism, and modern physics without even using calculus. And there are also graduate level books on these topics that make these introductory books look like next to nothing.
Well, it's very subjective what you define as "the best physics book". I'm a theoretician, and my all-time favorites are (in that order)
A. Sommerfeld, Lectures on Theoretical Physics (6 vols.)
R. Feynman et al, The Feynman Lectures (3 vols.)
L. D. Landau, Lifshitz et al Course on Theoretical Physics (10 vols.)
S. Weinberg, The Quantum Theory of Fields (3 vols.); Lectures on Quantum Mechanics; Gravitation and Cosmology (1971), Cosmology (2008)
J. Kapusta, C. Gale, Thermal Field Theory
Separate names with a comma.