We proposed an study of the black hole loss information starting from Thermodynamics and Black Hole Mechanics. The Bekenstein-Hawking entropy formula was derived and used to understand the implications of Hawking Radiation. Apart from this, we studied some concepts of singularity in General Relativity and Quantum gravity to understand the first model of loss information in black holes and why Black Hole Information Paradox is an unsolved problem in Physics at the present time.