Laptop will not power up

On battery or AC power? Have you cleaned the fan, vents, heatsink? Use a can of compressed Air to remove dust build up. If the Laptop overheats it will shut down to save the components from damage. You may want to try another Cord/charger with the EXACT same power specs. Have you set Sleep and Hibernate, in Advanced Power settings, to Never?

Go to Power Options --> On the plan you are using select change plan settings --> Change advanced power settings --> Scroll down till you reach battery and click the + next to it to expand the settings --> Where it says Critical battery level and Critical battery action (on battery) make sure that the level is at 5% and the action is to hibernate. If it's set to do nothing, it will keep running until it's out of battery and completely shut off. Plugging the AC adapter would give it more power. If that isn't the problem, check your battery's connection and consider replacing the battery.

This solution may sound stupid, but it is affective. Try to press really long time (about 1-2 minutes) on the power button of the laptop. wait for it to shut down completely. Then turn it on to see what happens.

What may have caused this is an update of any sort.

take battery out, unplug ac adapter. Wait one minute. leave battery out. Plug in ac adapter and turn on laptop. Once it turns back on. Shut down laptop and put battery back in. Now you should be able to turn laptop on with or without battery.

Laptops/notebooks are configured to go into sleep or hibernate modes after so many minutes of inactivity. The amount of time varies whether laptop is plugged in to AC power or running from battery. You can change the amount of time and how the power button behaves by changing your power managment settings in the control panel.

First of all, what I'm about to tell you are general troubleshooting techniques - I make no claim that they will fix what you describe, but they may help lead you to a solution.

1. Unplug the AC adapter and remove the battery
2. Plug in the AC adapter and attempt to power on the laptop
3. If it doesn't power on, see #6 below. If it does power on, but doesn't boot the OS, restart - pressing [SPACE] as the first Windows splash screen appears. When prompted, choose to delete the hibernation file and start a system boot.
4. Shut the system down, disconnect the AC adapter, reinsert the battery, and attempt to power the laptop. If it doesn't start we know, at the very least, there's a battery problem.
5. Plug in the AC adapter. If it shuts down immediately, or won't power back on after a shutdown. . .
6. . . .there's a problem with the system board, probably the ciruitry associated with charging the battery.

I hope you 'see the light'. Good Luck!

Does your laptop really shut down or is it going into hibernation mode. The way you can check is to enter the control panel and click on the power options. You will find power options for both battery and AC operation. Listed there is the time that the computer will run without any input before it goes into hibernation mode. If you wish to increase that time, just enter a different time. Or you can choose the "never hibernate" option.
See if that works for you. I'm assuming that your computer is just sitting there with no activity when this happens. If this is not the case, then we have to do a bit more troubleshooting.

I would suggest you just plug it in and do not power on the laptop for a few hours. Then try. If it persists reboot into safe mode and disable hibernation then reboot

Some laptops have issues with Windows XPs hibernation mode. To get the computer back up again you should just hold the power button down until it shuts off completely. Some laptops won’t shut off even if you do this. When this happens you have to take the battery out to get it to turn off. Make sure it is not plugged into the wall when you do this otherwise it wont work.

Once you get the computer back running again you may want to disable hibernation if it seems like its going to keep happening. Go to Start, Settings Control Panel or Start, Control Panel and go to the Power Options icon. Change the hibernation section to never. You may want to try standby as an alternative. Standby saves all your running applications and documents into RAM while hibernate saves them to the hard drive. Hibernate uses less power from your battery, but it will take you considerably longer to get the computer back up. If you always plug the computer in then you may want to disable standby and hibernate since you really dint need them while plugged in.

Let me know if this works.

try to open ur laptop cover .
on the mainboard there is usually a jumper located near the cmos battery. try to change its position for 3 seconds and return it back to its normal position.
this way u will clear the board memory .
start ur computer and load default settings.
hope this will help.