Dear Saravana kumar,

First of all best of luck for your JEE Main 2019.Start with a positive mindset to achieve something for your future.Its never late to start for acheiving something you aspire.Make sure you maintain the same momentum from the start. 

Keeping in mind that you have hardly one month for your JEE Main , I suggest you to thorough ncert books for basic understanding of concepts. Each and every section of ncert is very important .

Secondly ,The best books subject vise are listed below:

PHYSICS:

H.C Verma vol 1,2  , D.C Pandey seies, Refer I.E Irodov and krotov for advance

CHEMISTRY:                                                                   

Organic Chemistry: First complete Himanshu pandey and then M.S.Chauhan for theory purpose refer  O.P tandon,

Inorganic Chemistry:NCERT Text book for mains and V.K Jaiswal   

Physical Chemistry:Narendra Avasthi and refer O.P.Tandon for theory purpose

MATHEMATICS:

R.D Sharma ,Arihant series of books and reference for furtheu practice S.L.Loney

The above mentioned books are mandotory to be completed thoroughly before the exam.And finally refer previous years JEE Mains papers for a clear cut idea.   

Also courses are available online in careers360.                                                                 

All the Best!

Hello aspirant, 

The best books for jee main physics are

Concepts of Physicsb yH. C. Verma

Fundamentals of PhysicsH by alliday, Resnick and Walker

The best ones for chemistry are

Modern Approach to Chemical Calculations by RC Mukherjee

Organic Chemistry by Solomons and Fryhle

Concise Inorganic by J. D. Lee

For mathematics, 

Higher Algebra by Hall and Knight

Coordinate Geometry by S.L. Loney

Differential and Integral Calculus by N. Piskunov

And there is online course by careers360 jee main knoked out.You can join careers360 course. 

Good luck