B.Tech

Congratulations for your percentage in class 12th. But I'm sorry to say that your JEE Mains score is too low to get admission in NIT
Try in some good private colleges which take admission on the basis of class 12th PCM marks.
Good luck.
Upvote if it is useful.

As per your marks, there is a very rare chance of you getting any college. But keep an eye on the counselling seats and you can try in the last round for some GFTIs.
Good luck.

It is very hard to get a college with this rank. However, use this link so that you can predict the college on the basis of the rank you have secured:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor
If you want to take admission in a college located in Delhi, then go for GGSIPU, it is a very good option.

Since you have not qualified JEE Mains therefore through JEE Main, you will not get any college. However, you can appear for other state level exams such as UPSEE, MHCET GUJEE, WBJEE, etc., or the exams conducted by private colleges like SRMJEE, LPU-NEST, ATIT, UPES-EAT, etc.
Just do hardwork and focus. Best of luck.

Yes, you can change your engineering branch in M.Tech.

Your chances are less of getting NITs but you can get colleges of your state, may be government colleges. Try JEE college predictor to get more information and insight about college & branch which you can get on the basis of your rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=4067795