My Phone Wont Turn On

ok at work last night my phone dropped to 15% no big deal. outside of work i made a few phone calls and then put it in the super mode or whatever it then died on my way home. i thought nothing of it and plugged it in. i found it weird that it wouldnt turn on after it had been on the charger for a half our so i was immediately frustrated, i then left it on the charger all night and it still is and it wont turn on. i am very annoyed because i need this phone to be working. so it is on the charger and wont turn on which is unsettling. if you have any idea whats going on please help....