B.Tech

Unfortunately, since you have done B.Tech in Instrumentation and control engineering, you do not qualify. You need to be a B.Sc in mathematics and computer education, or any other degree that has math and or computer education. But, you can do it now. So, do it if you really want to get into M.Sc Ma

Memorise every formula physics chemistry. this will prevent u from losing marks because you
forgot the formula

B.Tech is not enough. You have to do M.Tech or MCA from reputed institute. You have to write GATE.

In June-July counseling for lateral student starts. Through counseling, you can get admission for B.Tech/BE.

Every college have different cutoffs, so according to that it is mentioned.

You can choose departments like mechanical, civil, electronics.

Sorry, but don't think you will get a government college, but you can try some other university examination.

NITs are the best option, if you want to do architecture and having a low fee structure. JEE Mains paper 2 can allot you the NITs for architecture.

You can go for the three year law degree course from any of the best universities in India. Even the five years integrated course can be an option.