Hello Omprakash,

yes,aap abhi bhi form fill kar sakte hai.

JEE main 2019 se 2 parts me hote hai ,ek january m or ek february me.

Aapka first attempt to Chhut chuka hai par ek Exam jo April m hone vali hai vo aap de sakte hai.

uske lie form February 8, 2019 ko niklega or iska last Date march 7 ,2019 ko hai .

JEE main k preparation ke lie mein aapko kuchh Books suggest kar rhi hu     

•         physics- NCERT(XI, XII), HC Verma(Volume I,II),  arihant publication for JEE main.
•         Chemistry -NCERT(XI,XII), Arihant publication of JEE main 
•         mathematics-R D Sharma,Haff and knight (algebra),SL Loney(cordinate Geomety and                trigonoetry)

if you completes your basics then deffinately you can score good marks in JEE main.

thank you so much

Wish you all the best for your exam.