My red ligth's on the ps3 controller keep flashng but never come on?

i restarted my ps3 all over because it keep showing in black and white now i restarted so it's lke i frist get it back it say's thati need to pug my usb line in and put the controller on it and i did that but the red ligth's on the controller keep flashing and never coming on which s really weior do i need a new controller or is it just not acting rigth? PLESEA HELP