How to get 15 day internship (instrumentation) for 15 days, without any references?

@Nandha‍ - My opinion is that 15 day internship will not be useful at all. You should at least aim for 2 months of internship. 

There are several online portals out there that offer internship related information. Internshala, I guess has a big database of internships. So, do search on that portal. 

As far as references are concerned, you don't really need them. Try online first and then try to approach those companies.

Sometimes, cold calling the companies may also do the trick. Do think about it.