April 14 (Reuters) - "Elon Musk has offered to buy Twitter (TWTR.N) for about $41 billion in cash, saying the social media company he has often criticized needs to go private to see effective changes. Musk's offer price of $54.20 per share, which was disclosedin a regulatory filing on Thursday, represents a 38% premium to Twitter's April 1 close, the last trading day before the Tesla (TSLA.O) CEO's more than 9% stake in the company was made public."