i feel as if im starting to lose my emotions.

I'm 17 and i have just been having these thoughts of why stay alive like i have nothing to live for and nothing matters like i feel if i died right now it would be the greatest thing that has ver happend to me and its not like anything has really caused this like i feel as if im starting to lose my emotions just having thoughts of dieing and the sad part is that it doesnt bother me idk if this is just a phase in my life but i feel almost positive it would be best just to die. i dont know what this means.and i havent always been like this im usally really happy one of the happiest people a person could know but everything has just turned around. -NTL4