Hello sandeep,

There are million websites and channels online to study you can even complete your course online itself, sometimes you also get certificates.Out of them I'm going to list you some of the best apps and websites for you,

1.Solo learn(application,also offers certificate)

2.Tutorials point(website)

3.Geeks for geeks(website good for programming)

4.Unacademy(application)

5.Stack overflow (you can ask any question or answer to any question you know).

Good luck,

Thankyou.