From where I can learn Blockchain completely

Answer 1

Internet

Answer 2

Look for 3Blue1Brown YouTube Video on Bitcoin. It is the best explanation of how it works and after that you can check the video description for further resources

Answer 3

You want to "master" blockchain development?
Learn:

C++
Python
Java
Solidity
Vyper
Golang
C#
JavaScript
Simplicity
Rholang

Answer 4

I advize against one-search Google searches or Youtube videos on this topic.

I haven't really seen any youtube video on this subject that did not have some sort of miss-information somewhere within it, although it is fine for getting a visual picture and general overall understanding.

Here are other resources on the subject that you may find helpful,

"Core Concepts, Challenges, and Future Directions
in Blockchain: A Centralized Tutorial"

Or "Blockchain Consensus Protocols in the Wild"

Oreilly also has a good article that might be an easier read. "Chapter 8: mining & consensus" for example.

You may also want to take a look at Bitcoins whitepaper. They use the term "timestamp server" to refer to the Blockchain.

Language is mostly irrelevant. You can use any. Solidity is largely for Etherium's smart contracts though.