Try pulling the battery for 10 minutes and putting it back in. Try pressing and holding the power button for a while 15-30 seconds to see if it will respond. Did anything happen to it, drop, submersion, etc. Was it functioning before you charged, When did it last work. Are you sure it charged up and the charger is working.
Have you tried holding the power and volume down buttons simultaneously for 15-30 seconds to see if that will reboot the phone? The DROID Razr's battery is nonremovable, so holding the power/volume down buttons simultaneously simulates a battery pull.