Need a bit of details here, what model, did anything happen before it stopped working? Does it not turn on at all or just no display on the screen? You can probably disconnect the battery if you open the case, you can try that, unplug the battery and remove CMOS battery if it's removable, hold in the power button for about 30 seconds, then plug in wall power only and see if that works. If it does, plug in the batteries and try again.