Delhi

You can consider following colleges:
Amity
Galgotias
Jaypee
NIT, Noida

Hi, Simran
Both the colleges are known for good faculty and infrastructure, so you can join any of these colleges.

You can go for B.Tech in mechanical engineering part time at low fee in Delhi from PGDAV along with your job.

Following are the colleges affiliated to DU:
1. St. Stephen's College
2. Miranda House
3. Hindu College
4. Sri Venkateswara College
5. Hansraj College
6. Ramjas College
7. Gargi College
8. Acharya Narendra Dev College
9. Deen Dayal Upadhyay College
10. Sri Guru Tegh Bahadur Khalsa College. The cut-off of these colleges is very high so you may not get the admission in the first few rounds. Further, JNU has its own entrance test for various UG programs, so you may try there.

Hi Prasenjit,
Yes, the admissions are still open. You can click below link for the details and online application:
http://www.inifdbangalore.com/admissions/

You can take admission in Amity University, Noida. It is the best university in a Delhi for B.Tech, but firstly, you can call Amity University admission cell. Phone number is available on the university's website.

Following are the few colleges offering B. Design:
1. NIFT, Delhi
2. Pearl Academy, Delhi
3. Amity University, Noida
4. World University of Design
5. Sharda University, Greater Noida.

No. Sorry, Ellen is in Jaipur only.

If you are general or OBC, then don't expect B.Sc. . Physics from DU in 83%. I got 93.6% in PCM & I got listed in the 5th cut-off. If you have at least 90%, then you can hope for it. But, you can do B.Sc. . Phy from other universities like IP, etc.