JEE

There are no chance of getting admission there, as of ST category the seats close within 1000 rank.

Yes, there are various institutes and coaching center for the entrance exams of NCHMCT JEE. If you wish you can enroll in any.
Please refer the link below for detailed information on the exams:
https://www.shiksha.com/hospitality-travel/hotel-hospitality-management/exams/nchmct-jee/admit-card
Regards

First of all which college? And, second thing is that I believe you didn't pass the NATA exam, as it is below the eligibility score (if not, then don't mind). And second thing is, that with these scores in both JEE and NATA it is impossible to get admission in a government architecture institution. You may try for some private colleges like Amity University or Galgotias University.

JEE Mains 2018 College Predictor
Use your JEE Mains 2018 rank to see where you can get admission at the link provided below:
See the courses, colleges & rounds you may crack
The result is based on admissions data of JEE Mains 2017
Get resources & insights on colleges & courses
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor.

You should drop if you think after appearing for the exam next year, you will clear it.
Although dropping a year is a good idea if you focus only on studies the whole year continuously, regularly and consistently.
All the best.

First, visit this link to check B.Arch colleges based upon your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=6919840
Then visit this link for various colleges which will provide you the brochure:
https://www.shiksha.com/architecture-planning/colleges/b-arch-colleges-india

First, visit this link to check B.Arch colleges based upon your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=6919840
Then visit this link for various colleges which will provide you the brochure:
https://www.shiksha.com/architecture-planning/colleges/b-arch-colleges-india

First, visit this link to check B.Arch colleges based upon your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=6919840
Then visit this link for various colleges which will provide you the brochure:
https://www.shiksha.com/architecture-planning/colleges/b-arch-colleges-india

First visit this link to check B.Arch colleges based upon your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=6919840
Then visit this link for various colleges which provides you brochure:
https://www.shiksha.com/architecture-planning/colleges/b-arch-colleges-india

First, visit this link to check B.Arch colleges based upon your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=6919840
Then visit this link for various colleges which will provide you the brochure:
https://www.shiksha.com/architecture-planning/colleges/b-arch-colleges-india