What Happens when you have no more cards in Your Magic Library

What would Happen when you have no more cards left in Your Magic Library?

Nothing really.

If you try to draw a card from an empty library though, you lose the game.

so why would i want to try and draw if library is empty and it would make me lose the game

Well, you have to draw at the start of your turn, and an opponent trying to win this way may have effects that make you draw.