Follow this steps

1.Ensure the notebook is connected to a working power source using the factory supplied AC Adapter. Ensure the AC wall plug is not controlled by a switch and that other devices on the same circuit are on.

NOTE: If the AC Adapter is connected to a power strip, surge suppressor or UPS, ensure the power strip, surge suppressor, or UPS is powered on and working properly.

2. Ensure the computer is fully shut down and powered off before trying to start the computer. To do this, push and hold the power switch for 15 seconds. This will ensure the computer has shut down and is not just in standby mode.

3. Press the Reset switch on the bottom of the notebook with a thin pointed object.

4. Disconnect the AC Adapter and remove the battery. Push and hold the power switch for at least 30 to 45 seconds. Reconnect only the AC Adapter and power on the notebook. If the notebook starts correctly, shut down the computer, reinstall the battery, and allow at least 2 hours to charge the battery before disconnecting the notebook from AC power.

NOTE: If the battery is not inserted properly or is loose, the notebook may not start even when using AC power.

5. Disconnect all external and added devices.

NOTES:

* This includes PC Cards, USB devices, i.LINK devices, external speakers, network and modem cables, etc.

* If the notebook starts, reconnect each device one at a time, restarting the notebook between each item. If the notebook fails to start after a specific item is connected, contact the manufacturer of the item for further support.

6. If the notebook is connected to an external monitor or projector, ensure it is properly connected, configured, and powered on. Ensure the brightness and contrast controls are set correctly. Refer to the users manual for the display for more information.

7. If the customer has recently installed additional RAM, remove the additional RAM and reseat the original RAM.

8. Moisture condensation may have occurred. Ensure the notebook is in a dry, environmentally controlled area and powered off for at least one hour.

You haven't specified the model # of your lap. You can get the exact troubleshooting steps for your computer from www.esupport.sony.com