You can trying turning it off by pressing the power button or you can also take off the battery and leave it for a couple of minutes. After removing the battery, press the power button to drain off any remaining power in the phone for about five to ten minutes, you can then put back the battery and turn the phone on. If this does not work, you can go to the place where you purchased it if it still has a warranty.
Turn it off for five minutes and close it down, remove the battery and wait; then place the battery back in and power it on. If this doesn't work, rub the batteries connecting areas and try reloading again?