It can't be downloaded from any website for free, You can purchase it from any book store or online. If you are preparing for NEET Entrance Exam then firstly I would suggest you to complete NCERT books as it will help you to clear your basics then you can prefer other books. The other books you can prefer below given:

Physics

Concepts of Physics by H. C. Verma

Objective Physics by DC Pandey

Fundamentals of Physics by Halliday, Resnick and Walker

Fundamental Physics by Pradeep

Problems in General Physics by IE Irodov

Physical Chemistry by OP Tandon

Chemistry

ABC of Chemistry for Classes 11 and 12 by Modern

Concise Inorganic Chemistry by JD Lee

Dinesh Chemistry Guide

Biology

Biology Vol 1 and Vol 2 by Trueman

Objective Biology by Dinesh

Objective Botany by Ansari

Pradeep Guide on Biology


Good Luck!