Why can't my phone turn on

I can't seem to turn my phone on no matter what i do, i have held the on button for 2mins a few times, i re put the battery many times. I am sure i never drop it, i was able to use it for a few times, but today i turn off when it was charging, and could not turn it on any longer. when i charge, the charging sign does not even appear, even after switching batteries , still same effect