I just closed the lid of my Sony VAIO VPCSE17GA (the laptop went into sleep mode). Returned after half an hour to find out it won't wake up again. Connected the charger, the lights would go on showing that the laptop is charging. Pressed the power button but no sign of startup is visible (no fan sound, no beep, no keyboard lights, nothing). What should I do to bring my laptop back to life?
Take the battery out, hold the power button for around fifteen seconds. This should restart the BIOS, which controls the startup and shutdown of your computer, among a multitude of other things. Source
If this doesn't work, you'll have to reset the CMOS battery. I could not find any instructions on how to reset the battery online, so you'll have to consult your instruction manual. You can try and have a look at this Google search result.