Who invented the language called 'HINDI'?

Answer 1

No one invented it. It evolved naturally from a language called Sanskrit, which in turn evolved from an unattested language known as Proto-Indo-European.

Answer 2

Hindi evolved from Sanskrit and is believed to have been standardized by scholars during the 19th century, with the development of the Devanagari script playing a key role. There isn't a single inventor of Hindi; rather, it is the result of centuries of linguistic evolution in the Indian subcontinent.