Try the following and see if it will turn on...
1. Unplug your charger cord.
2. Remove the battery.
3. Press and hold the "Power" button for 30 seconds.
4. Now plug back in the power/charger cord.
5. Now put the battery back in and try starting it up again.
Should that not work, see if you can go into BIOS as the computer starts up and reset it to the default settings.
If that also doesn't work, you may have to try reinstalling Windows.