How do I prepare for JEE Mains and JEE Advanced 2017 in drop year?

First, you need to be focused and self determined.

Mathematics:

1-Make sure you can solve problems from the NCERT class XI and class XII textbooks.
2-For best concepts, use IIT Mathematics for JEE (Main and Advanced) by M.L. Khanna
3-For the most abundant supply of difficult questions: New Pattern IITJEE Mathematics by Dr. S.K. Goyal
4-Plane Trigonometry and Elements of Coordinate Geometry by S.L. Loney

Physics:

1-Concepts of Physics, Volumes 1 and 2, by H.C. Verma
2-Problems in General Physics, by I.E. Irodov
3-Fundamentals of Physics, by Halliday, Resnick, and Walker
4-Understanding Physics for JEE Main and Advanced (series), by D.C. Pandey

Chemistry:

1-Study the NCERT chemistry textbooks for classes XI and XII.
2-Organic Chemistry, by Morrison and Boyd
3-Numerical Chemistry for JEE Main and Advanced, by P. Bahadur
4-Concise Inorganic Chemistry, by J.D. Lee
5-Modern Approach to Chemical Calculations, by R.C. Mukherjee
6-Physical Chemistry, by P. Bahadur.
7-organic, physical, and inorganic chemistry books by O.P. Tandon