Hello Siddhartha,

You can appear for NIOS definitely but the problem is most colleges do not accept NIOS board results as legitimate during admission. You will have to roll in a NIOS university after this, then. If your goal is to enter college through any state-level or nation-level exam such as JEE or NEET then your NIOS certificate won't matter and you can get admission in good college despite it. Some colleges do not care much for ISC marks and give importance to their own entrance exams. There are a lot of good colleges that have their ISC cut offs really low, you can pass their entrances and apply there.

Hope this helps.